PubMed Health⌕ Search

Biomedical subjects

C S Sun

Publications and source records attributed to C S Sun.

At least 19 recordsLinked to original sources
PubMed2003

Increased neurosteroid sensitivity of hippocampal GABAA receptors during postnatal development.

To investigate developmental changes in neurosteroid modulation of GABA(A) receptors, whole-cell currents were elicited by applying GABA with allopregnanolone or pregnenolone sulfate (PS) to dentate granule cells (DGCs), acutely isolated from 7-14-day-old and adult rats. GABA evoked larger currents from dentate granule cells acutely isolated from adult rats (adult DGCs) than from neonatal DGCs, due to increased efficacy (1662+/-267 pA in adult DGCs versus 1094+/-198 pA in neonatal DGCs, P=0.004), and current density (0.072+/-0.01 pA/microm(2) in neonatal rat DGCs to 0.178+/-0.02 pA/microm(2) in adult DGCs), but unchanged potency (EC(50) was 18.5+/-2 microm in adult DGCs, and 26.6+/-7.9 microm in neonatal DGCs, P=0.21). Allopregnanolone sensitivity of GABA(A) receptor currents increased during development due to an increased potency (21.1+/-4.7 nM in adult DGCs versus 94.6+/-9 nM in neonatal DGCs, P=0.0002). The potency and efficacy of PS inhibition of GABA(A) receptor currents were remained unchanged during development (13+/-6 microm and 13.2+/-5.9 microm, P=0.71 and 85.5%+/-3.5% and 83.6%+/-0.8%, P=0.29, respectively). To investigate possible mechanism of developmental changes in GABA(A) receptor properties, in situ hybridization for alpha1, alpha4 and gamma2 subunit mRNAs was performed in dentate gyrus of the two age groups. Qualitatively, alpha1 subunit mRNA was expressed at low levels in neonatal rats while it was well expressed in adult rats. The alpha4 and gamma2 subunits were well expressed in the dentate gyrus of adult and neonatal rats. Immunohistochemical staining for alpha1 subunit in hippocampal slices from neonatal and adult rats was examined under confocal laser scanning microscope. This demonstrated that cell bodies and dendrites of granule cells are moderately positive for the alpha1 staining in adult rats but weakly so in neonatal rats. Higher-magnification images demonstrate large number of clusters of alpha1-subunit in the cell bodies of dentate granule cells of adult rat but rare clusters in granule cells of neonatal rats. Maturation of GABA(A) receptors in DGCs is characterized by increased number of GABA(A) receptors that are more sensitive to endogenous neurosteroid allopregnanolone, which might be related to increased expression of alpha1 subunit.

Aging↗
PubMed2000

Evaluation and validation of virus removal by ultrafiltration during the production of diaspirin crosslinked haemoglobin (DCLHb).

Virus retention during ultrafiltration through A/G Technology filter cartridges was investigated to characterize the removal process and validate the degree of virus titre reduction during the filtration of red blood cell haemolysates performed as part of the production of diaspirin crosslinked haemoglobin (DCLHb). When viruses were suspended in phosphate buffered saline solution, retention was greater with larger sized viruses and smaller filter pore size. Virus titre was maintained at starting levels in the filter retentate circuit during the course of filtration, suggesting that the virus removal mechanism is predominantly size exclusion. Evaluation of specific processing variables indicated that the retention of phiX174 virus was increased in the presence of red blood cell haemolysate or at high membrane crossflow rates and transmembrane pressures, while the retention of EMC virus was less sensitive to variations in these parameters. Using these results to design a validation protocol, log reduction values of >7.9 were demonstrated for the retention of human immunodeficiency virus, pseudorabies virus and bovine viral diarrhoea viruses, 7.6 for hepatitis A virus, and 4.2 for porcine parvovirus. It was also shown that the retention of viruses was maintained during repetitive use of the same filter cartridge.

Animals↗
PubMed1999

Development of fungal mycelia as skin substitutes: effects on wound healing and fibroblast.

In this study, Sacchachitin membrane, prepared from the residue of the fruiting body of Ganoderma tsugae, was estimated for its effects on wound healing and the proliferation and migration of fibroblast cells. Two mirror-image wounds were made on the back of female guinea pigs by dissecting a 1.5 x 1.5 cm2 skin surface of full thickness. Sacchachitin membrane was placed randomly on one of the wounds and gauze or Beschitin on the other. Changes in the wound area were measured and photographed after a predetermined amount of time postoperatively. Histological examination of the wound and surrounding tissue was also performed to reveal any interaction of tissue with the dressing. The results showed that the wound area covered with Sacchachitin membrane was statistically smaller than that covering with gauze on day 10, whereas there was no significant difference in the wound size compared to that with Beschitin. Fibroblast cells from the dermis layer of guinea pigs were used. The number of fibroblast cells were counted on the predetermined days in the culture suspended with or without 0.01% w/v dressing materials. By layering on DMEM plates, the number of fibroblast cells migrating across the center line or outside of the central hole were counted after five days. All the results indicated that both 0.01% w/v of Sacchachitin and chitin significantly enhanced the proliferation and migration of fibroblast cells.

Animals↗
PubMed1997

The in vitro anti-HIV efficacy of negatively charged human serum albumin is antagonized by heparin.

Succinylated human serum albumin (Suc-HSA) was synthesized by treating human serum albumin with succinic anhydride. Among similar proteins and neo(glyco)proteins tested, Suc-HSA exhibits a pronounced net negative charge, a feature that largely contributes to its efficacy against replication of human immunodeficiency virus type 1 (HIV-1). To assess further the antiviral effect of Suc-HSA, the effect on HIV-1 replication was studied in the presence of whole human plasma. Pretreatment of MT2 cells with Suc-HSA was more efficacious than direct Suc-HSA treatment of HIV prior to addition to the cells. No changes in the antiviral effect of Suc-HSA were observed in tissue culture medium, 30% plasma, or whole plasma when CPDA-1 (citrate-phosphate-dextrose-adenine 1) was used as the anticoagulant. However, a dramatic decrease (greater than 99%) in the antiviral activity was observed when these experiments were performed in plasma prepared from blood using heparin as anticoagulant. The antagonistic effect by heparin was observed both in the case that heparin was added prior to or after addition of Suc-HSA to the test system. In the present study we demonstrate that heparin largely reduces Suc-HSA activity on HIV replication in the same concentration in which if affects binding of Suc-HSA to the envelope protein gp120 and in particular its V3 domain. In the same concentration range, heparin reduced binding of Suc-HSA to MT4 cells, another HTLV-I-transformed cell line. It is concluded that heparin can displace Suc-HSA from its binding sites on hybrid lymphoid cells as well as on HIV-1 particles. Therefore, we conclude that both the binding to cells and to virus contribute to the potent anti-HIV-1 effect. The fact that heparin and heparin degradation products antagonize Suc-HSA without having a significant anti-HIV-1 effect indicates that the anticoagulant acts as a relatively weak partial inhibitor.

Anti-HIV Agents↗
PubMed1997

Fungal mycelia as the source of chitin and polysaccharides and their applications as skin substitutes.

A wovenable skin substitute (Sacchachitin) made from the residue of the fruiting body of Ganoderma tsugae was developed in this study. Chemical analysis revealed that the treated residue was a copolymer of beta-1,3-glucan (ca 60%) and N-acetylglucosamine (ca 40%) with a filamental structure of mycelia form, as demonstrated by both optical and scanning electron microscopy. The pulp-like white residue was then woven into thin, porous sheets 7.0 cm in diameter and 0.1-0.2 mm in thickness by filtration and lyophilized for use as a skin substitute. The wound area produced by dissecting rat skin of full thickness was found to almost completely heal on the side covered with Sacchachitin, whereas the control side covered with cotton gauge was around 6.0 cm2 on the 28th day. Furthermore, the wound healing effects of the chitin sheet from crab shell (Beschitin) and Sacchachitin were not found to be significantly different.

Acetylglucosamine↗
PubMed1994

Polymorphisms of complement component I and C1R subcomponent of C1 in nine aboriginal Taiwanese populations.

Complement component I (IF) and C1R subcomponent of C1 (C1R) types were determined by isoelectric focusing and subsequent immunoblotting techniques for 658 individuals from nine aboriginal Taiwanese populations. The frequency of the IF*A allele ranges from 0.075 (Bunun) to 0.430 (Saisiat), and a new variant allele IF*B2 was found to have polymorphic frequency in the Atayal. The frequency of the C1R*1 allele ranges from 0.410 (Yami) to 0.650 (Atayal), and the frequency of the C1R*2 allele ranges from 0.265 (Atayal) to 0.586 (Saisiat). The C1R*5 allele was found in five populations (Atayal, Bunun, Ami, Puyuma, Yami), and the C1R*9 allele was found in two populations (Tsou, Puyuma). The results indicate a remarkable degree of genetic variability among these populations. The variability may reflect long-term genetic and geographic isolation of each population.

Alleles↗
PubMed1993

Seroepidemiological survey of human T-lymphotropic retrovirus among indigenous populations in Taiwan.

The prevalence of human T-lymphotropic retrovirus (HTLV) was examined in Taiwan's indigenous populations. In all, 797 healthy subjects in Taiwan including Han Chinese and nine indigenous populations (Ami, Atayal, Bunun, Saisiat, Paiwan, Puyuma, Rukai, Tsuo, and Yami) were examined for the presence of antibodies to HTLV by particle agglutination, indirect immunofluorescence and Western blot test. Two seropositive cases were found in this screening. One Saisiat male and a Han Chinese female were seropositive for HTLV. The Western blot profile indicated the virus was type-1 HTLV.

Adult↗
PubMed1993

Hepatitis B viral clearance studies using duck virus model.

We have shown data to suggest that the in vivo duck hepatitis B virus system represents an excellent animal model system for the study of hepatitis B virus. Because of the similarity of DHBV to human HBV (including comparable results in virus inactivation studies), the high level of sensitivity of the DHBV assay, and the rapidity, ease, and relative low cost of obtaining results, we propose that the in vivo DHBV titration system be used as a model for human HBV in process validation studies. Data generated in such validation studies have, in fact, been submitted by a number of blood products manufacturers to the U.S. F.D.A. in support of IND applications.

Animals↗
PubMed1993

[Synthesis and platelet aggregation inhibitory activity of 6-substituted dihydropyridazinones].

In order to develop more potent and less toxic antithrombotic agents, ten 6-(4-substituted piperazinyl acetyl aminophenyl)-4,5-dihydro-3(2H)-pyridazinones were synthesized. The title compounds were tested in vitro for platelet aggregation inhibitory activity with ADP-induced rat platelets and PAF-induced rabbit platelets. Preliminary tests showed that all of the pyridazinones could inhibit ADP-induced rat platelet aggregation. I7, I8, I9 were more potent than the control compound CI 930. I9 was the most potent compound with IC50 of 0.99 mumol/L. Pertaining to PAF-induced rabbit platelet aggregation, I9 was the most potent inhibitor with IC50 of 3.7 mumol/L.

Animals↗
PubMed1992

Validation of virus inactivation by heat treatment in the manufacture of diaspirin crosslinked hemoglobin.

Diaspirin crosslinked hemoglobin (DCLHb), a hemoglobin based oxygen carrying solution prepared from outdated human blood, is subjected to a heat treatment step to inactivate viruses in our manufacturing process. To validate the efficacy of this inactivation, we have simulated the heat treatment procedure at a reduced scale using hemoglobin solution spiked with representative viruses. Human Immuno-deficiency Virus (HIV), Cytomegalovirus (CMV), and Duck Hepatitis B Virus (DHBV) were used in this validation. Inoculation with concentrated virus was performed just prior to the heat treatment to determine the effect of that specific process step. Samples were taken before, during, and after heat treatment and assayed for virus titer in an attempt to assess the rate as well as the extent of virus inactivation. CMV was analyzed in a plaque assay using MRC-5 indicator cells. The titer was reduced from 3.3 x 10(6) plaque forming units (PFU) per mL to less than 5 x 10(1) PFU/mL (detection limit) within 30 minutes. DHBV was analyzed by inoculation of serially diluted samples into Pekin ducklings, followed at intervals by screening sera for DHBV DNA by dot blot hybridization. The titer was reduced from 5.0 x 10(6) duck infectious units (DIU) per mL to less than 5 x 10(0) DIU/mL (detection limit) within 1 hour. HIV titers were determined through an ELISA assay for p24 antigen present in peripheral blood lymphocyte cocultivation supernatants. The titer was reduced from 2.0 x 10(4) infectious units (IU) per mL to less than 2 x 10(0) IU/mL (detection limit) within 1 hour. These data indicate that high titers of these blood borne viruses are rapidly inactivated by this heat treatment process.

Aspirin↗
PubMed1990

[Synthesis and platelet aggregation inhibitory activity of 6-(4-substituted phenyl)-4,5-dihydro-3(2H)-pyridazinones].

To search for more ideal antithrombotic drugs sixteen 6-(4-substituted phenyl)-4,5-dihydro-3(2H)-pyridazinones were designed and synthesized. Some improvement of the synthetic method involved in constructing the piperazinyl group by cyclization of bisbromoethyl amine with 4-pyridazinonyl anilines. Preliminary pharmacological tests showed that all of the target compounds inhibited ADP induced platelet aggregation. Compounds II2, II3 and II4 were more potent than CCI-17810. The 5-methyl derivative of CCI-17810 (II4) was the most potent compound.

Animals↗
PubMed1989

Inactivation and removal of human immunodeficiency virus in monoclonal purified antihemophilic factor (human) (Hemofil M).

Cold supernatant which was prepared from factor VIII:C containing cryoprecipitate was seeded with HIV-1, then treated with a mixture of tri (n-butyl) phosphate (TNBP) and triton X-100. A greater than 10(11)-fold reduction of HIV-1 infectivity was observed. In a separate experiment, cold supernatant which had been seeded with HIV-1 was chromatographed on an immunoaffinity column, resulting in a 10(4)-fold reduction of infectivity. None of the 17 patients treated with the purified product and followed for at least three months has shown serologic evidence of HIV-1 or other viral infections.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Limited efficacy of aerosolized recombinant alpha interferon against virulent influenza A/HK infection in mice.

Hybrid recombinant human alpha interferon A/D (rIFN A/D) is unusual in that it has equivalent antiviral activity in in vitro assays using mouse or human tissue cells. This interferon was delivered to outbred Swiss mice in small particle aerosols before and/or after these mice were inoculated with virulent influenza A/HK/68 virus. Although rIFN A/D was effective in inhibiting influenza virus replication in vitro in primary mouse embryo cells, it had only a limited degree of effectiveness in the in vivo tests; only animals exposed to rIFN A/D for 4 hr and inoculated with influenza virus 4 hr later exhibited a significant decrease in mortality (approximately 25% reduction in deaths; P less than 0.025) compared with that of the untreated control animals. The limited effectiveness of rIFN A/D seen in these studies indicated that the use of this or similar recombinant alpha interferons alone to prevent or treat influenza virus infection in humans is not promising.

Aerosols↗
PubMed1985

Duration of effect of interferon aerosol prophylaxis of vesicular stomatitis virus infection in mice.

Mice were exposed for 8 h to continuous small-particle aerosols containing natural mouse alpha interferon (estimated dosage 100 U per mouse) or one of two concentrations of hybrid recombinant alpha interferon A/D bgl (estimated dosages of 100 and 10,000 U per mouse, respectively). On days 1, 3, 5, 7, and 9 after exposure to these interferons, three mice from each group were inoculated intranasally with 100 PFU of vesicular stomatitis virus. Control mice were exposed to aerosols of saline or inoculated intraperitoneally with either natural mouse alpha interferon (350 U) or one of two doses of hybrid recombinant alpha interferon A/D bgl (350 or 35,000 U) and challenged similarly. Of mice injected intraperitoneally, only those given 35,000 U of hybrid recombinant alpha interferon A/D bgl 24 h before virus challenge were protected from pulmonary infection, compared with the saline-treated control mice. Of mice given 100 U of either interferon by small-particle aerosol, only those exposed 24 h before inoculation of vesicular stomatitis virus had reduced pulmonary titers of the virus. However, of mice given ca. 10,000 U of hybrid recombinant alpha interferon A/D bgl by small-particle aerosol, all groups except those exposed 9 days before virus inoculation had significantly reduced lung virus titers.

Aerosols↗
PubMed1984

Efficacy of aerosolized recombinant interferons against vesicular stomatitis virus-induced lung infection in cotton rats.

Cotton rats (Sigmodon hispidus) were inoculated intranasally with vesicular stomatitis virus (VSV) and exposed to different regimens of small particle aerosols of either recombinant human alpha interferon A (rIFN-alpha A) or hybrid recombinant human alpha interferon A/D (rIFN-alpha A/D). Preliminary in vitro tests indicated that both recombinant IFNs were effective in protecting primary cotton rat pulmonary cells against VSV replication. However, rIFN-alpha A/D was 20-fold more active than rIFN-alpha A in these tests. In the in vivo tests, in contrast to control animals inoculated with VSV, but not treated, or treated only with aerosols of saline, animals exposed to either rIFN-alpha A or -alpha A/D for 8 h per day before and/or following VSV inoculation had no detectable virus titers in their lungs. In experiments in which groups of animals were treated for shorter periods, rIFN-alpha A was less effective than rIFN-alpha A/D in suppressing replication of VSV in lungs of these animals.

Aerosols↗