Biomedical subjects

T Peng

Publications and source records attributed to T Peng.

At least 73 records · Page 4Linked to original sources

PubMed1997

Glycoprotein D of herpes simplex virus (HSV) binds directly to HVEM, a member of the tumor necrosis factor receptor superfamily and a mediator of HSV entry.

Glycoprotein D (gD) is a structural component of the herpes simplex virus (HSV) envelope which is essential for virus entry into host cells. Chinese hamster ovary (CHO-K1) cells are one of the few cell types which are nonpermissive for the entry of many HSV strains. However, when these cells are transformed with the gene for the herpesvirus entry mediator (HVEM), the resulting cells, CHO-HVEM12, are permissive for many HSV strains, such as HSV-1(KOS). By virtue of its four cysteine-rich pseudorepeats, HVEM is a member of the tumor necrosis factor receptor superfamily of proteins. Recombinant forms of gD and HVEM, gD-1(306t) and HVEM(200t), respectively, were used to demonstrate a specific physical interaction between these two proteins. This interaction was dependent on native gD conformation but independent of its N-linked oligosaccharides, as expected from previous structure-function studies. Recombinant forms of gD derived from HSV-1(KOS)rid1 and HSV-1(ANG) did not bind to HVEM(200t), explaining the inability of these viruses to infect CHO-HVEM12 cells. A variant gD protein, gD-1(delta290-299t), showed enhanced binding to HVEM(200t) relative to the binding of gD-1(306t). Competition studies showed that gD-1(delta290-299t) and gD-1(306t) bound to the same region of HVEM(200t), suggesting that the differences in binding to HVEM are due to differences in affinity. These differences were also reflected in the ability of gD-1(delta290-299t) but not gD-1(306t) to block HSV type 1 infection of CHO-HVEM12 cells. By gel filtration chromatography, the complex between gD-1(delta290-299t) and HVEM(200t) had a molecular mass of 113 kDa and a molar ratio of 1:2. We conclude that HVEM interacts directly with gD, suggesting that HVEM is a receptor for virion gD and that the interaction between these proteins is a step in HSV entry into HVEM-expressing cells.

Animals↗

PubMed1996

The novel protein kinase of the RR1 subunit of herpes simplex virus has autophosphorylation and transphosphorylation activity that differs in its ATP requirements for HSV-1 and HSV-2.

The large subunit of herpes simplex virus (HSV) ribonucleotide reductase (RR1) designated ICP6 and ICP10 for HSV-1 and HSV-2, respectively, has a novel protein kinase (PK) enzymatic activity. ICP10 is localized on the cell surface, a localization that depends on an intact transmembrane (TM) segment. We used immunocomplex PK assays to examine the PK activity of ICP10 in stably transfected eukaryotic cells. Activity was distinct from that of casein kinase II (CKII) in that it did not require monovalent ions and was not inhibited by zinc sulfate. PK activity was eliminated by deletion of the conserved PK catalytic motifs or of the TM segment and it was significantly impaired by mutation of the invariant Lys (Lys176). Loss of PK activity by Lys176 mutation resulted in the failure to bind ATP. A truncated ICP10 PK expressed in bacteria (pp29 1a1) retained auto- and transphosphorylating activity (for calmodulin) after purification to apparent homogeneity. PK activity was also absent in cells infected with a recombinant virus (ICP10 delta PK) deleted in the ICP10 PK catalytic motifs. In cells infected with HSV-1 or HSV-2, RR1 had auto- and transphosphorylating activity for the small subunit of HSV ribonucleotide reductase (RR2) and immunoglobulin G (IgG). Comparing the PK activity of ICP6 and ICP10 we found that ICP6 requires five-fold higher concentrations of [gamma-32P]ATP than ICP10 and both enzymes are Mn2+ dependent, which is also different from CKII that is primarily Mg2+-dependent. Similar results were obtained for various HSV strains and in different cell lines. The data are consistent with the conclusion that the RR1 PK activity is intrinsic.

Adenosine↗

PubMed1996

Role of polymers in improving the results of stenting in coronary arteries.

This article is a review of recent developments of polymer-related stents mainly employed in the coronary arteries, including polymer-coated stents, biostable stents and biodegradable stents. Polymer paving is covered as well. The problems with the stents currently investigated and the development of new stents are discussed.

Adsorption↗

PubMed1996

Cerebrospinal fluid antibodies detected by ELISA against a 33-kDa antigen from spherules of Coccidioides immitis in patients with coccidioidal meningitis. The National Institute of Allergy and Infectious Diseases Mycoses Study Group.

Antibodies against a 33-kDa antigen from Coccidioides immitis were detected by ELISA in patients' cerebrospinal fluid (CSF). Anti-33-kDa antibodies were detected at dilutions > 1:80 in only 1 (1.4%) of 73 patients without coccidioidal meningitis but in 74 (71.8%) of 103 with meningitis. Anti-33-kDa antibodies were detected in 53 (91.4%) of 58 patients whose anti-coccidioidal complement-fixing (CF) antibodies were detectable and in 21 (46.7%) of 45 patients whose CSF was negative by CF test (positive predictive value, 99%; negative predictive value, 71%; sensitivity, 72%; specificity, 99%). Anti-33-kDa antibodies, among which IgG1 was the dominant subclass, increased when infections worsened and decreased when patients' conditions improved. Antibody concentration appeared to be independent of most baseline findings, although only 1 of 5 patients coinfected with human immunodeficiency virus had initially detectable antibodies. Measurement of anti-33-kDa antibodies is a sensitive indicator of coccidioidal meningitis and of its clinical course.

Antibodies, Fungal↗

PubMed1996

Detection of coccidioidal antibodies by 33-kDa spherule antigen, Coccidioides EIA, and standard serologic tests in sera from patients evaluated for coccidioidomycosis.

During a 9-month study of patients being evaluated for coccidioidomycosis, 1 or more serum samples were obtained from 138 patients with an illness suggestive of recent infection. In this group, standard immunodiffusion tests of unconcentrated sera were positive for 25; 49 additional patients had at least 1 reactive test result by newer enzyme-linked serologic tests. At least 11 of these 49 patients had coccidioidomycosis as determined by culture or subsequent standard serologic tests. Patients with coccidioidomycosis identified only by newer tests had fewer or milder clinical abnormalities than did patients in whom the disease was detected by standard tests. For 31 other patients with illness of a chronic or undetermined duration, newer tests detected only 10 more than the 18 identified by standard tests, suggesting that later in the course of illness, standard testing gains in sensitivity for coccidioidal infection.

Antibodies, Fungal↗

PubMed1996

[Inhibition of experimental metastasis and cell adhesion of B16 murine melanoma cells by protein kinase C inhibitor CJ9111].

Treatment of B16 murine melanoma cells with different concentration of CJ9111 for various time in culture and subsequent i.v. injection of the cells into C57BL/6 mice resulted in dose and time dependent inhibition of lung metastasis. The 50% inhibition concentration (IC50) of metastasis with CJ9111 was 8 micrograms/ml, a value similar to that for the inhibition of B16 cell membrane-associated PKC (IC50 = 63 micrograms/ml). B16 cells treated with CJ9111 for 24 h were less adherent than untreated cells to endothelial cells. These results suggest that PKC may be a key element in regulating tumor-cell metastasis and PKC inhibitors may be promising agents in the control of metastasis.

Animals↗

PubMed1996

Effect of verapamil on Ca2+ influx and CVB3-RNA replication in cultured neonatal rat heart cells infected with CVB3.

The effect of verapamil on Ca2+ influx across the myocardial plasma membrane and coxsackie virus B3 (CVB3) -RNA replication in cultured neonatal rat heart cells infected with CVB3 was investigated. It was found that the Ca2+ influx could be inhibited significantly (P < 0.01) by verapamil (1 mumol/L) after infection of heart cells for 48 h. However, when the cultured heart cells infected with CVB3 and treated with verapamil (1 mumol/L and 10 nmol/L) at the same time for 48 h, the amounts of CVB3-RNA in myocytes were significantly higher than that in infected control group (P < 0.05). These phenomena suggest that the increase of Ca2+ influx of cultured heart cells infected with CVB3 could be inhibited by some calcium antagonists, e.g. verapamil at the early stage. On the other hand, verapamil might accelerate viral replication in myocardium. Thus, although verapamil could be beneficial for decreasing the secondary Ca2+ damages and improve the myocardial electric activity, it isn't a sensible choice for therapy in early stage of virus infection with cardiac symptoms.

Animals↗

PubMed1995

Reproductive isolation between Drosophila lini and its siblings.

Courtship behavior and reproductive isolation between nine strains of Drosophila lini and its siblings from Taiwan (TWN), Dinghushan (DHS) and Nankunshan (NKS) in China, and Pyinoolwin (MMY) and Yangon (RGN) in Myanmar were investigated. No premating and postmating isolation between the Taiwan and mainland China strains were found. Crosses between mainland China (DHS and NKS) or the TWN strain and the MMY or RGN strain produced fertile F1 hybrid females and sterile F1 hybrid males. Crosses between MMY strains and RGN strains which showed strong premating isolation produced either no F1 hybrids, or fertile F1 hybrid females and sterile males in some cases. These results suggest the existence of at least three genetically distinct sibling species of D. lini.

Animals↗

PubMed1995

Enhanced adeno-associated virus vector expression by adenovirus protein-cationic liposome complex. A novel and high efficient way to introduce foreign DNA into endothelial cells.

Adeno-associated virus vector (AAV), a non-pathogenic integrating vector, can integrate on chromosome 19 in humans. But its gene transfer efficiency is quite low. In this study we combined adenovirus (Adv-5) capsid protein or the Fiber protein of Adv with liposome, termed adenosome (adenovirus protein-cationic liposome complex). This complex can bring AAV/CMV-LacZ to the endothelial cells, and improve the efficiency of gene transfer. It may be a novel, specific, stable and safe gene delivery system and will be widely used in human gene therapy.

Adenoviruses, Human↗

PubMed1995

Adenovirus mediated gene transfer of vascular smooth muscle cells and endothelial cells in vitro.

Introducing foreign gene(s) into vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) is the pre-requirement of gene therapy for cardiovascular diseases. We have explored the use of adenoviral vectors (Adv-CMV/LacZ) to transfer LacZ gene into cultured VSMCs and ECs. Our results demonstrated that adenoviral vectors transferred foreign gene into VSMCs and ECs high-efficiently with dose-dependent response pattern. The frequencies of transfection reached 100% at the viral titer of 10(9) pfu/ml. Comparing the sensitivities of VSMCs and ECs to adenoviral vectors, we found that ECs were more sensitive than VSMCs, of which the frequencies of transfection in ECs reached 80% while in VSMCs only 40% for 8 hrs after transfection. In addition, the transfection of ECs and VSMCs with adenoviral vectors was partly blocked by monoclonal antibodies to Fiber and Core protein of the adenoviral capsid, but not by monoclonal antibody to Hexon protein. It is suggested transfection of ECs and VSMCs with adenovirus vectors is mediated by Fiber or Core protein of adenoviral capsid proteins.

Adenoviruses, Human↗

PubMed1995

The inhibitory effect of astragalus membranaceus on coxsackie B-3 virus RNA replication.

Using mice infected with coxsackie B-3 virus (CVB3) as a viral myocarditis model, we observed the inhibitory effect of Astragalus membranaceus (AM) on CVB3-RNA replication in myocardial tissue of mice by RNA-RNA in situ hybridization with negative-strand RNA probes labelled with 35S and quantitative imaging analysis of positive signals. The mechanism of its effect on CVB3-RNA replication has been investigated by detection of beta-interferon (beta-IFN) as well. Results showed that the copy numbers of CVB3-RNA as well as the histologic scores (necrosis) in myocardial tissues of infected-AM treated mice were significantly lower than those in infected and normal saline treated mice, suggesting that AM could inhibit the replication of CVB3-RNA, but its effect on CVB3-RNA replication had no correlation with induction of beta-IFN.

Animals↗

PubMed1994

Controlled release of albumin from chitosan-alginate microcapsules.

A polymeric delayed-release protein delivery system was investigated with albumin as a model drug. The polysaccharide chitosan was reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane. Variables believed to be important for membrane formation were examined; these included reaction time, chitosan molecular weight, alginate concentration, chitosan concentration, and solution pH. An alginate-chitosan reaction time, in the range of 10 to 45 min, had no effect on the release of albumin. Increasing the alginate concentration, however, resulted in a decreased rate of release of albumin (from 37% release at 4 h with 1.5% alginate to 20% release with 2.5% alginate). Another key variable was the chitosan molecular weight. The molecular weight of chitosan was varied from 1.25 x 10(6) to 0.25 x 10(6) through a nitrite oxidation reaction with sodium nitrite. Decreasing the molecular weight increased the release of albumin (from 37% release at 4 h with high molecular weight chitosan to 77% release with low molecular weight chitosan). The pH of the extracapsular environment was found to affect the release of albumin significantly (15% release over 24 h at a pH 3.0 and 73% release at pH 8.0). Capsules produced with high molecular weight chitosan and a combination of high and low molecular weight chitosan gave the best results for reducing elution of albumin in the first 4 h and increasing elution in the following 20 h.

Albumins↗

PubMed1994

The sex ratio of suicide rates in China.

Suicide is the leading cause of non-natural deaths in China. Female suicide rates are higher than male rates, and the rural suicide rate is 2.8 times higher than the urban rate. In 16,568 cases of suicide, the male to female ratios observed were 0.92 and 0.81 in urban and rural areas, respectively. The male to female ratio of the suicide rates in China is close to that of other Asian countries (1.2-1.5), but much lower than that in 26 European countries. In about two-thirds of all suicides, family disputes and love disappointments are the precipitants. The higher rate of suicide among women probably reflects the fact that Chinese women are of low social and economic position, and have few social resources to protect them, especially in remote areas.

Cause of Death↗

PubMed1994

[Site-directed mutagenesis at Ser177 of penicillin G acylase gene].

Site-directed mutagenesis was performed at Ser177 of Penicillin G Acylase (PGA) gene of E. coli by gap duplex method. Screened by 2-nitro-5-phenylacetaminobenzoic acid (NIPAB) test paper assay and confirmed by DNA sequencing, the mutants Cys177, Gly177, Arg177 and Asn177 were obtained. They have no activity of PGA. The mutant enzyme was expressed and detected by PAGE. It is suggested that Ser177 is at the substrate binding center of PGA and can not be replaced.

Base Sequence↗

PubMed1993

Function and origin of multiple ionic forms of hormone-induced ornithine decarboxylase.

Ornithine decarboxylase (ODC) occurs in liver and kidney of control and hormone-treated rats as two ionic forms, A and B in order of elution, separable by ion-exchange chromatography of cell-free extracts. These studies were designed to investigate the origin of the multiple forms and their role in the hormonal stimulation of ODC activity. The percentage of activity present in A and B was determined in liver (73/27) and kidney (50/50) of control animals. The proportion of activity present as form B had increased by approximately 15% at 5 h after treatment with dexamethasone, prolactin, or growth hormone. In tissues of control rats, the half-life of both A and B was short, in the range of 7-11 min. The half-life of form A was unchanged after hormone treatment, but the half-life of B increased 2- to 3-fold in liver and 5- to 15-fold in kidney. When hormone-treated rats received LiCl 0.5-1 h before sacrifice, ODC activity was less than that after hormone treatment alone, the proportion of activity in A and B reverted to that present in control animal tissues, and the half-life of B reverted to the range of 7-10 min. Thus the production or maintenance of the enhanced stability of B is disrupted by lithium. A post-translational modification of A could be responsible for producing the more acidic and more stable B in the hormone-treated rats. A 3- to 5-fold increase in ODC mRNA occurred in kidney of rats treated with dexamethasone or prolactin, and was largely reversed by LiCl. Stimulation of ODC in kidney by growth hormone did not involve a major change in ODC mRNA, nor was the amount affected by LiCl.

Animals↗

PubMed1993

In vitro studies of a new antifungal triazole, D0870, against Candida albicans, Cryptococcus neoformans, and other pathogenic yeasts.

We investigated the effects of various assay conditions on the activity of D0870 against seven species of fungi in the broth macrodilution testing procedure proposed by the National Committee for Clinical Laboratory Standards (NCCLS). Multivariate analysis demonstrated that endpoint definition, starting inoculum size, medium composition, type of buffer, and length of incubation, but not pH or temperature, had significant effects on results. Increasing the inoculum from 10(2) to 10(5) yeast cells/ml raised the MICs for all isolates up to > 75,000 fold. This effect was greatest when endpoints corresponded to a 90% reduction in visually determined turbidity (MIC90), was less prominent with an 80% inhibition visual endpoint (MIC80), and was nearly absent with a 50% endpoint measured by a spectrophotometer (IC1/2). Differences due to medium composition were attributable to antibiotic medium 3 with RPMI and yeast nitrogen base media performing nearly identically. Under standardized conditions as specified in NCCLS document M27-P (Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts; Proposed Standard, 1992), 79 strains (5 to 25 strains for each species) demonstrated median MIC80s of 0.0037 and 0.0075 microgram/ml for Candida albicans and Cryptococcus neoformans, respectively. In contrast, Candida krusei and Torulopsis glabrata had a median MIC80 of 1.0 microgram/ml. Our studies indicate that the pathogenic yeasts C. albicans and C. neoformans are more susceptible to D0870 than other pathogenic yeasts.

Antifungal Agents↗

PubMed1992

Effect of lithium chloride on ornithine decarboxylase activity in rat adrenal.

The effects of lithium chloride on ornithine decarboxylase (ODC) activity were compared in the adrenal and kidney of control (saline treated) and prolactin-treated rats. ODC activity was decreased in kidney of both groups of animals, the magnitude of the effect of lithium in the hormone-treated group varying with the time of administering the lithium relative to prolactin. The response in the adrenal was quite different. Following treatment with LiCl, there was a gradual increase in ODC activity from a low of 10-35 pmol CO2 x 30 min-1.mg protein-1 in control animals to values 20- to 30-fold greater at 5 h. In rats treated simultaneously with LiCl and prolactin, ODC activity was greater at 5 h than that observed in animals receiving either compound alone, indicating that their effects were additive. When LiCl was given 4 h after prolactin, i.e., 1 h before sacrifice, ODC activity decreased to a very low level at 5 h, as in other tissues. The increase in ODC activity in the adrenal following LiCl is of the same magnitude as the changes observed in tissues stimulated to undergo alterations in proliferation, differentiation, or metabolic or membrane activity by hormones and other external stimuli.

Adrenal Glands↗

PubMed1992

[The experimental studies of the effect of Forskolin on the lowering of intraocular pressure].

The effect of the domestic Forskolin on lowering the intraocular pressure (IOP) of rabbits was studied. The results showed that the Forskolin significantly lowered the normal IOP of rabbits and blocked the ocular hypertension induced by water load in rabbits (p < 0.01). The maximum decrease value of 2%, 1% and 0.5% of the Forskolin was 0.59. 0.36 and 0.19 kPa (1 kPa = 7.5 mmHg), which showed the noticeable dose-effect relationship. Topical ocular application of Forskolin lowered IOP in 1/2 hour, reached to a peak in 2-3 hours and remained significantly for 10 hours. The pupillary diameter did not change when IOP were reduced. Furthermore, the Forskolin had potent stimulative properties to adenylate cyclase (AC). The greater the ability of the Forskolin to stimulate AC, the stronger the effect of IOP lowering.

Adenylyl Cyclases↗