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Biomedical subjects

Y Y Wang

Publications and source records attributed to Y Y Wang.

At least 19 recordsLinked to original sources
PubMed1992

Postvaccinal sarcomas in the cat: epidemiology and electron probe microanalytical identification of aluminum.

An increase in fibrosarcomas in a biopsy population of cats in the Pennsylvania area appears to be related to the increased vaccination of cats following enactment of a mandatory rabies vaccination law. The majority of fibrosarcomas arose in sites routinely used by veterinarians for vaccination, and 42 of 198 tumors were surrounded by lymphocytes and macrophages containing foreign material identical to that previously described in postvaccinal inflammatory injection site reactions. Some of the vaccines used have aluminum-based adjuvants, and macrophages surrounding three tumors contained aluminum oxide identified by electron probe microanalysis and imaged by energy-filtered electron microscopy. Persistence of inflammatory and immunological reactions associated with aluminum may predispose the cat to a derangement of its fibrous connective tissue repair response, leading to neoplasia.

Aluminum↗
PubMed1992

Alterations of pulse by Chinese herb medicine.

Rats were injected with the crude extract of Chinese herbs, Rhizoma Coptidis, Radix Bupleuri and Cinnamomum cassia Blume. The pulse of the tail artery were examined. The results indicated that each drug had a specific effect on the Fourier components of the pulse.

Animals↗
PubMed1992

Characterization of muscarinic receptor subtypes in canine left ventricular membranes.

The pharmacological characteristics of muscarinic receptor (mAChR) subtypes in canine left ventricular membranes (LVM) were determined using [3H] quinuclidinyl benzilate ([3H]QNB) and [3H]N-methyl scopolamine ([3H]NMS) as ligands. Binding of [3H]QNB and [3H]NMS was saturable with respect to the radioligand concentrations. Analysis of binding isotherms by Scatchard plot showed that [3H]QNB and [3H]NMS bound to an apparently homogeneous population of mAChRs in LVM, with KD values of 390 +/- 100 and 285 +/- 34 pM and Bmax values of 240 +/- 20 and 133 +/- 9 fmol/mg protein, (n = 6), respectively. The Hill coefficients for [3H]QNB and [3H]NMS binding were 0.95 +/- 0.02 and 0.99 +/- 0.01, respectively. Based on the competitive inhibition of [3H]ligand binding, atropine and NMS as well as the selective M1 antagonist PZ revealed no selectivity for these mAChRs. PZ competed with [3H]QNB or [3H]NMS for a single binding site with a Ki value of 0.23 +/- 0.03 microM and 0.62 +/- 0.10 microM, (n = 6), respectively, which is close to the values of M2 or M3 receptors. The data indicate that the M1 receptor subtype did not exist in canine LVM. Competition of [3H]ligand binding with selective M2 antagonists, AF-DX 116 and methoctramine and the selective M3 antagonists, 4-DAMP and hexahydrosiladifenidol, gave a best fit for a two-binding site model. The inhibition of carbachol-mediated phosphoinositide hydrolysis by PZ, AF-DX 116 and 4-DAMP, generated an affinity profile for this response also dissimilar to that described for the classical cardiac M2 response. Although no other muscarinic receptor mRNA has been detected in this tissue, these data suggest the presence of a second population of muscarinic sites, which may signify an M2 receptor diversity.

Animals↗
PubMed1992

Biomedical engineering basis of traditional Chinese medicine.

Traditional Chinese medicine is an ancient medical science that can be traced back for three to four thousand years of written history. Using the transient response characteristic method, we studied the frequency property of some simulated organs. We tried to explain the concept that the energy in the blood pressure wave is distributed to different organs in the body according to the frequency. This will elucidate the ancient teaching of Chinese medicine in terms of current engineering terminology.

Biomedical Engineering↗
PubMed1991

Electronic excitation transfer in the complex of lumazine protein with bacterial bioluminescence intermediates.

Fluorescence dynamics measurements have been made on the bioluminescence reaction intermediates using Photobacterium leiognathi, Vibrio fischeri, and Vibrio harveyi luciferases, both alone and in mixtures with Photobacterium phosphoreum lumazine protein. Each luciferase produces a "fluorescent transient" intermediate on reaction with the bioluminescence substrates, FMNH2, tetradecanal, and O2, and all have a fluorescence quantum yield about 0.3, with a predominant lifetime around 10 ns. The P. leiognathi luciferase fluorescent transient has a rotational correlation time of 79 ns at 2 degrees C, as expected for the rotational diffusion of a 77-kDa macromolecule. In the presence of lumazine protein however a faster correlation time of about 3 ns predominates. This rapid channel of anisotropy loss is attributed to energy transfer from the flavin intermediate bound on the luciferase to the lumazine ligand, reflects the presence of protein-protein complexation, and is greatest in the case of P. leiognathi, but not at all for V. fischeri. This fact is consistent with the strong influence of lumazine protein on the bioluminescence reaction of P. leiognathi, and not at all with V. fischeri. The rate of energy transfer is of order 10(9) s-1, much greater than the 10(8) s-1 fluorescence rate of the donor. Thus the bioluminescence excitation of lumazine protein could occur by a similar photophysical mechanism of interprotein energy transfer from a chemically excited fluorescent transient donor to the lumazine acceptor.

Bacterial Proteins↗
PubMed1991

Seasonal variations and trends in concentrations of filter-collected polycyclic aromatic hydrocarbons (PAH) and mutagenic activity in the San Francisco Bay area.

Air monitoring in the San Francisco Bay Area was carried out to measure outdoor community air concentrations of polycyclic aromatic hydrocarbons (PAH) and mutagenic activity (mutagenicity) in particulate organic matter (POM). Monitoring began in 1979 and is currently conducted at six stations. PAH and mutagenicity tests were performed on organic extracts prepared from high volume (hi-vol) filters composited every four months, by meterological season. PAH were determined by high pressure liquid chromatography (HPLC) with fluorescence and ultraviolet detection. Mutagenicity was measured in the Ames Salmonella bioassay using strain TA98 with and without metabolic activation. The nine-year mean concentration of benzo(a)pyrene (BaP) was 0.4 ng/m3. The mutagenicity of this amount of BaP accounted for only about 0.2% of the observed mutagenicity in POM and other measured PAH accounted for even less. Concentrations of PAH and mutagenicity were three to nine times higher during the winter than during other seasons. Year-to-year wintertime trends in several PAH were also seen. Early in the 1980s, winter concentrations of BaP and benzo (g,h,i)perylene increased. However since the mid-1980's, their concentrations have fallen. The decrease in PAH concentrations may be the result of an increasing proportion of vehicles with relatively low organic emissions. In contrast to PAH, mutagenicity did not show significantly year-to-year time trends.

Air Pollutants↗
PubMed1991

Resonance. The missing phenomenon in hemodynamics.

To simulate a short segment of the aorta, we studied wave propagation in an elastic tube with a side branch balloon. The small balloon simulated the organ (group of arterioles). Ligation of this side branch would reduce the moduli of the higher harmonics when the length of the side branch was appropriate. Electrical analogy of vessels was used to analyze this phenomenon. This simulation can explain the ligation results we found in rats. It may also clarify the discrepancies between the prediction of the Womersley equation and the experimental results. We suggest that the aorta and the closely attached organ can produce coupled oscillation; theoretically, this structure is equivalent to a resonance circuit.

Animals↗
PubMed1990

Enzymatic and NMR analysis of oligoribonucleotides synthesized with 2'-tert-butyldimethylsilyl protected cyanoethylphosphoramidite monomers.

The regioisomeric integrity of the internucleotide phosphate linkage in synthetic RNA using 2'-tert-butyldimethylsilyl protection was examined using enzymatic and NMR techniques. Two sets of DNA-RNA hybrid nonamers, T3XT5 and T5XT3 (where X = rA, rC, rG and U) and the tetramer AGCU were analyzed. Enzyme catalyzed hydrolysis of the nonamers with ribonuclease T2 showed that the linkage at the ribonucleotide was the desired 3'-5'. A control nonamer with a 2'-5' linkage was subjected to the enzyme, and showed no cleavage. High-resolution proton NMR of the tetramer also gave a favorable comparison with the same molecule obtained by non-chemical means.

Base Sequence↗
PubMed1990

Tumor resistance to alkylating agents conferred by mechanisms operative only in vivo.

EMT-6 murine mammary tumors were made resistant to cis-diamminedichloroplatinum (II) (CDDP), carboplatin, cyclophosphamide (CTX), or thiotepa in vivo by treatment of tumor-bearing animals with the drug during a 6-month period. In spite of high levels of in vivo resistance, no significant resistance was observed when the cells from these tumors were exposed to the drugs in vitro. The pharmacokinetics of CDDP and CTX were altered in animals bearing the respective resistant tumors. The resistance of all tumor lines except for the EMT-6/thiotepa decreased during 3 to 6 months in vivo passage in the absence of drugs. These results indicate that very high levels of resistance to anticancer drugs can develop through mechanisms that are expressed only in vivo.

Alkylating Agents↗
PubMed1990

Antiviral strategies in chronic hepatitis B virus infection: I. Establishment of an in vitro system using the duck hepatitis B virus model.

Primary duck hepatocyte (PDH) cultures were established from ducklings congenitally infected with the duck hepatitis B virus (DHBV), plated onto feeder cell layers of irradiated human embryonic lung fibroblasts, and observed for 2 to 3 weeks. This system permitted the survival of the PDH in a differentiated form free of fibroblastic overgrowth for at least 3 weeks. The hepatocytes were shown to contain all the replicative DNA intermediates found during DHBV replication as well as the DHBV structural proteins PRE-S1, PRE-S2, and S of duck hepatitis B surface antigen (DHBsAg). The pool of supercoiled (SC) DHBV DNA increased dramatically from days 10 to 14 postplating. This PDH-feeder cell layer cell culture model provides a convenient system to study the effects of conventional inhibitors of DHBV replication and compounds targeted at the supercoiled form of DHBV DNA. This approach should allow the evaluation of a variety of strategies for treating chronic carriers of hepadnaviruses.

Animals↗
PubMed1990

Antiviral strategies in chronic hepatitis B virus infection: II. Inhibition of duck hepatitis B virus in vitro using conventional antiviral agents and supercoiled-DNA active compounds.

Primary duck hepatocyte (PDH) cultures, congenitally infected with the duck hepatitis B virus (DHBV), were grown on feeder cell layers of irradiated human embryonic lung fibroblasts and then exposed to a number of compounds with recognized or potential antiviral activity. These compounds included conventional antiviral agents, reverse transcriptase inhibitors, compounds with activity to supercoiled-DNA, and DNA-binding agents. Twenty-three compounds were evaluated, and 13 were found to inhibit significantly viral DNA replication. Seven of these compounds (ellipticine, amsacrine, coumermycin A1, Adriamycin, mitozantrone, chloroquine, and neocarzinostatin) acted at the level of viral SC DNA and significantly inhibited production of duck hepatitis B surface antigen (DHBsAg). Conventional agents that inhibited DHBV DNA replication included ganciclovir, acyclovir, bromovinyldeoxyuridine, ribavirin, phosphonoformate, and dideoxyadenosine. Except for dideoxyadenosine, these inhibitors of viral DNA synthesis did not significantly inhibit DHBsAg production. Two additional compounds, novobiocin and nalidixic acid, altered the pattern of viral DNA replication, especially the generation and processing of viral SC DNA, and also inhibited the production of DHBsAg. Several compounds acting at the level of viral SC DNA have now been identified and may offer potential for the management of chronic hepatitis B virus infection.

Animals↗
PubMed1990

Effect of Phyllanthus amarus on duck hepatitis B virus replication in vivo.

Nine ducks congenitally infected with the duck hepatitis B virus (DHBV) were treated either orally (four ducks for 10 weeks) or intraperitoneally (five ducks for 12 weeks) with the Indian traditional herbal remedy Phyllanthus amarus. Compared to placebo-treated control ducks, these treatments did not result in a reduction of circulating viral DNA in the serum or in the level of viral DNA replication in the liver. In two of the five intraperitoneal-treated ducks, a reduction in the levels of duck hepatitis B surface antigenaemia (DHBsAg) was observed. The data strongly suggest that Phyllanthus amarus has no significant inhibitory effect on DHBV DNA replication and only a minor effect on DHBsAg production.

Animals↗
PubMed1990

Recovery of components of fluorescence spectra of mixtures by intensity- and anisotropy decay-associated analysis: the bacterial luciferase intermediates.

Reaction of FMNH2 and O2 with bacterial luciferase followed by blue light irradiation results in a product previously claimed to have the same fluorescence spectral distribution as the bioluminescence. Preparations of this "high fluorescence" intermediate, however, contain two fluorescent components, one from the intermediate and the other its breakdown product, FMN. Since the intermediate has a fluorescence lifetime of around 10 ns and a rotational correlation time in the range of 100 ns, compared to 5.0 and 0.15 ns, respectively, for the FMN, the two components can be successfully resolved from the total fluorescence by an anisotropy decay- and fluorescence decay-associated analysis employing simultaneous global computational methods. The fluorescence spectra of the intermediates from two types of luciferase were analyzed in this way; one luciferase was from Vibrio harveyi and the other was from an unusual type of V. fischeri that had an in vivo bioluminescence maximum at 505 nm, a wavelength almost 20 nm longer than that of the V. harveyi bioluminescence. For V. harveyi the true fluorescence of the intermediate is distinct from the bioluminescence, being found at a wavelength about 10 nm longer. For the type of V. fischeri examined, any difference in the two spectra is less certain. A control experiment with the dye 8-amino-1- naphthalenesulfonate bound to BSA and mixed with FMN recovered the original spectrum of the bound dye accurately.

Animals↗
PubMed1990

Transverse location of anthracyclines in lipid bilayers. Paramagnetic quenching studies.

Quenching of anthracycline fluorescence by a series of spin-labeled fatty acids was used to probe the transverse location of the drug in phosphatidylcholine bilayers in the form of small unilamellar vesicles. Stern-Volmer plots of the quenching data indicate that the fluorophore moiety of the anthracycline is intercalated into the hydrocarbon region of the bilayer, with deeper penetration observed in fluid-phase than in solid-phase vesicles. 31P-NMR parameters (T1 and nuclear Overhauser enhancement (NOE] are unaffected by the presence of drug, consistent with a binding site removed from the interfacial region. Comparison of intensity (F0/F) plots with lifetime (tau 0/tau) data shows that the predominant mechanism of anthracycline quenching by membrane-bound nitroxides is static. Since the membrane-bound drug is also accessible to quenching by I-, the binding site in the membrane must create a channel which is accessible to solvent. Two other fluorescent probes, 12-(9-anthroyloxy)stearate (12-AS) and diphenylhexatriene (DPH), were employed to confirm the results obtained with the anthracyclines, giving quenching data representative of their location in the bilayer.

Antibiotics, Antineoplastic↗
PubMed1990

In vivo activity of an islet-reactive T-cell clone.

BDC-6.9 is a CD4-positive T-cell clone, specific for NOD islets, which was isolated from the spleen and lymph nodes of a diabetic NOD mouse. The cells were transplanted in a blood clot adjacent to established NOD islet grafts in diabetic (CBA X NOD)F1 recipients. The BDC-6.9 cells initiated extensive damage to the islet grafts, while a non-islet specific clone transplanted adjacent to grafted islets caused no noticeable damage. In addition, the BDC-6.9 cells initiated similar destruction when injected intraperitoneally, suggesting that they may have some migratory capacity. By introducing these islet-reactive cells into the (CBA X NOD)F1, a non-diabetes prone environment, we hope to clarify the role of the islet-specific CD4 cell as related to islet destruction in vivo.

Animals↗