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Biomedical subjects

S N Chen

Publications and source records attributed to S N Chen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Perfluorodecalin condensation on posterior surface of lens capsule and corneal endothelium during vitrectomy.

BACKGROUND: High-density vitreous substitutes, including perfluorodecalin, are widely used in current vitreoretinal surgery. We report 4 cases of perfluorodecalin condensation on the posterior capsule of the lens or corneal endothelium during vitrectomy. To the best of our knowledge, no such phenomenon has ever been reported. METHODS: This study consisted of 4 patients with retinal detachment and large retinal tears. All patients were men. All of the patients underwent pars plana vitrectomy, perfluorodecalin injection, endolaser retinopexy and air-fluid exchange. Two patients received additional surgery for scleral buckling. RESULTS: Perfluorodecalin condensation was observed on the posterior surface of the lens capsule in one phakic patient and on the endothelium in three aphakic patients during vitrectomy. The condensation obscured the image of the fundus and made air-fluid exchange difficult. The condensation could be dissipated by first removing the perfluorodecalin as completely as possible, and then by lowering the intraocular pressure below the vapor pressure of perfluorodecalin. CONCLUSIONS: Perfluorodecalin condensation may occur when perfluorodecalin is not properly used. To avoid forming condensation, high-density vitreous substitutes should never be injected into eyes that are completely air-filled, prolonged air-fluid exchanges should be avoided, and the intraocular pressure should always be kept at a higher level during air-fluid exchange.

Adult↗
PubMed1999

Establishment of cell lines derived from oyster, Crassostrea gigas Thunberg and hard clam, Meretrix lusoria Röding.

The present study attempts to establish cell culture systems for the oyster, Crassostrea gigas Röding and the hard clam, Meretrix lusoria Thunberg. Treatment with collagenase was better than trypsin at dissociating mollusc tissue fragments for in vitro culture. Heart tissue of oyster and hard clam proved to be the most promising target tissue for the establishment of cell lines in vitro. Primary cultures of clam heart were established and successfully maintained for more than 5 months. Collagenase at a concentration of 100 microg/ml may enhance the growth of oyster and hard clam heart cell cultures in vitro.

Animals↗
PubMed1999

Establishment of cell culture systems from penaeid shrimp and their susceptibility to white spot disease and yellow head viruses.

Monolayer cultures were established from ovary, heart, lymphoid tissue and peripheral hemocytes of penaeid shrimps including Penaeus monodon, P. japonicus and P. penicillatus. The most favorable conditions for the culture of penaeid shrimp cells in vitro was in CMRL and L-15 tissue culture media when used within an osmolarity range of 620--760 mmol/kg. The optimal maintenance temperature was 25 degrees C for tissues of P. japonicus and 28 degrees C for tissues of P. monodon and P. penicillatus. Among the four tissues tested, lymphoid tissue, or 'Oka organ', was superior to the other tissues for the formation of confluent cell monolayers. Cell cultures from lymphoid tissue and ovary have been subcultured up to three times. When peripheral hemocytes and heart were cultured, a maximum survival of 4 days was obtained. In contrast, cell cultures derived from ovary and lymphoid tissue were maintained alive for at least 20 days in appropriate culture systems. Neither confluent cell sheet nor adherence of cells was obtained in cultivation of hepatopancreas using the present culture systems. The results obtained from the present study also revealed that ovary extract, muscle extract and lobster hemolymph enhanced the survival of the cultured cells of penaeid shrimp in vitro. When the 'Oka organ' cell monolayer was incubated with either white spot disease virus (WSDV) or yellow head virus (YHV), no cytopathic effect (CPE) was obtained. However, at 5--7 days after establishment, significant CPE (a few foci) was observed in cell monolayers derived from WSDV- and YHV-infected Oka tissue. By electron microscopy, virions of WSDV and YHV were observed in the nuclei and cytoplasm of cultured cells. The CPE foci developed further with increased incubation time.

Animals↗
PubMed1998

An intravitreal sustained-release triamcinolone and 5-fluorouracil codrug in the treatment of experimental proliferative vitreoretinopathy.

OBJECTIVE: To determine the efficacy and pharmacokinetics of an intravitreal sustained-release triamcinolone acetonide and 5-fluorouracil (TA/5-FU) codrug in the treatment of experimental proliferative vitreoretinopathy (PVR). METHODS: The therapeutic efficacy of the TA/5-FU codrug was determined in a rabbit model that simulates human PVR. Intravitreal levels of triamcinolone and 5-fluorouracil were measured at different time points and drug release in vitro was tested. Toxic effects were evaluatedby electroretinograpy, clinical examination, and light microscopy. RESULTS: Both the severity of PVR grade and the percentage of eyes with moderate or worse tractional detachment were significantly less in eyes treated with the codrug. The therapeutic effect of the intravitreal codrug was paralleled by sustained intravitreal levels of triamcinolone and 5-fluorouracil. There were no drug-related toxic effects evident on clinical or histopathologic examination of eyes containing the TA/5-FU codrug. CONCLUSIONS: The intravitreal sustained-release TA/5-FU codrug effectively inhibits the progression of PVR in a rabbit model that closely resembles PVR in humans. The TA/5-FU codrug may simultaneously target different components of the wound-healing response.

Animals↗
PubMed1997

Purification and characterization of a cysteine protease produced by pathogenic luminous Vibrio harveyi.

The purification and characterization of an extracellular protease produced by pathogenic luminous Vibrio harveyi strain 820514, originally isolated from diseased tiger prawn (Penaeus monodon), was presented in this paper. The purification steps included ammonium sulfate precipitation, with columns of hydrophobic interaction chromatography and anion exchange on fast protein liquid chromatography. The protease is an alkaline cysteine protease, heat labile, inhibited by iodoacetamide, iodoacetic acid, N-ethylmaleimide, p-chloromercuribenzoate, and p-chloromercuribenzene-sulfonic acid, and showed maximal activities at pH 8 and 50 degrees C, having a molecular mass of 38 kDa as estimated by SDS-PAGE and gel filtration column. In addition, the protease was also completely inhibited by CuCl2 and HgCl2, but not or only partially inhibited by other inhibitors tested. Furthermore, 2-mercaptoethanol was the most effective reducing agent in the activation of the enzyme. The present protease is the first cysteine protease found in Vibrio species.

Cysteine Endopeptidases↗
PubMed1997

Passive immunization of the tiger prawn, Penaeus monodon, using rabbit antisera to Vibrio harveyi.

Passive immunization, toxicity neutralization and the persistence of passive protection in the tiger prawn (Penaeus monodon) were investigated using rabbit antisera to the formalinized extracellular products (ECP) (R alpha ECP) and/or formalinized bacterial cells (R alpha BC) of luminescent Vibrio harveyi strain 820514 originally isolated from diseased tiger prawns. Rabbit antiserum to bovine serum albumin (R alpha BSA) or phosphate-buffered saline (PBS, pH 7.2) both served as controls. The toxicity of ECP to prawns was neutralized by pre-incubation with R alpha ECP. Passive immunization by pre-injection of R alpha BC or R alpha ECP into prawns 3 d in advance protected against a lethal dose challenge of bacteria. To determine the persistence of passive protection by rabbit antiserum in tiger prawns, the R alpha BC, R alpha ECP, R alpha BSA or PBS were injected into prawns. At 10, 17 or 24 d post-immunization, groups of prawns were given a lethal dose challenge of bacteria. The prawns in the two control groups were all killed within the first 2 d following challenge at all three challenge dates. Pre-injection with R alpha BC and R alpha ECP provided total protection for 10 and 17 d, respectively, with all treated prawns surviving for at least 2 weeks post-challenge. This is the first study using mammalian antisera to investigate toxicity neutralization, passive immunization and persistence of passive protection by rabbit antisera in prawns. The results could be useful in future studies on virulence mechanisms and disease control of vibriosis in cultured prawns.

Animals↗
PubMed1997

HLA polymorphism and probability of finding HLA-matched unrelated marrow donors for Chinese in Taiwan.

Tzu Chi Taiwan Marrow Donor Registry (TCTMDR) was established in 1993 to recruit and HLA-type volunteers who would be willing to donate bone marrow. TCTMDR is currently the largest marrow registry for Chinese in the world, with over 150,000 prospective donors registered as of July 1997. We present here the gene and haplotype frequencies based on 80,353 HLA class I-typed and 18,217 HLA class II-typed healthy Chinese in Taiwan. The resulting frequencies are used for estimating the probability of finding an HLA-matched donor for a patient. The common HLA class I antigens include A1 (gene frequency: 32.9%), A2 (29.7%), A24 (17.5%) and A33 (11.0%); B60 (18.1%), B46 (12.8%), B58 (9.8%) and B13 (7.8%); Cw3 (51.4%), Cw1 (11.6%) and Cw7 (8.6%). The common HLA class II antigens are DR4 (16.6%), DR9 (15.6%), and DR12 (14.0%); DQ7 (20.7%), DQ9 (12.7%), and DQ5 (12.1%). The common two-locus haplotypes observed with a P-value less than 0.001 are A2-B46 (haplotype frequency: 8.5%), A33-B58 (7.5%), A11-B60 (6.6%); B58-DR17 (7.0%), B46-DR9 (6.4%) and B60-DR4 (4.9%). The common three-locus haplotypes are A33-B58-DR17 (5.3%), A2-B46-DR9 (3.9%) and A11-B60-DR4 (2.0%). As expected, the gene frequency pattern of Taiwanese is more closely related to that of southern Hans than to the pattern of northern Hans, Japanese, Caucasians and African-Americans. Using our registry, 323 of 571 domestic patients (57%) successfully identified one or more matched donors. The empirical result correlated well with a mathematical simulation having an estimated 59% match when donor pool reaches 150,000.

Asian People↗
PubMed1997

Susceptibility of different isolates of Vibrio harveyi to antibiotics.

The susceptibility of six Vibrio harveyi strains to antibiotics was studied. Four strains originally isolated from diseased penaeids and two reference strains originally isolated from either sea water (ATCC 25919) or diseased Talorchestia sp. (ATCC 14126) were used in the present study. Results revealed that all three strains isolated in Taiwan exhibited resistance against nitrofurantoin, novobiocin and sulphonamide. The two reference strains and the strain isolated in Indonesia were susceptible to these three antibiotics.

Animals↗
PubMed1996

Isolation of Vibrio harveyi from diseased kuruma prawns Penaeus japonicus.

Outbreaks of high mortality among the cultured kuruma prawn Penaeus japonicus without overt gross signs occurred during August and December of 1994 in I-Lan, Taiwan. Eleven luminous bacterial strains were isolated from the hepatopancreas of moribund prawns from five different farms by use of tryptic soy agar (TSA, supplemented with 2% NaCl) and/or thiosulfate citrate bile salt sucrose (TCBS) agar. These strains, together with our two previously unpublished isolates, were characterized and identified to be Vibrio harveyi in comparison with two ATCC Type strains and one strain previously isolated from the tiger prawn, P. monodon.

Animals↗
PubMed1996

Condensation on polymethylmethacrylate, acrylic polymer, and silicone intraocular lenses after fluid-air exchange in rabbits.

PURPOSE: Condensation occurs rapidly on silicone intraocular lenses (IOLs) after vitrectomy and fluid-air exchange in the presence of a posterior capsulotomy, severely limiting the retinal view. Foldable IOLs made of an acrylic polymer are now available. The authors compare the condensation and subsequent retinal view degradation after vitrectomy and fluid-air exchange in rabbit eyes implanted with polymethylmethacrylate (PMMA), soft acrylic polymer (ACRYSOF), and silicone IOLs. METHODS: Thirty rabbits underwent bilateral lens removal. Twenty PMMA, 20 acrylic polymer, and 20 silicone IOLs were implanted into the capsular bag. After three-port vitrectomy, eyes were randomly assigned to undergo a posterior capsulotomy or to an intact posterior capsule. Fluid-air exchange was performed, and the amount of condensation on the IOL surface and resultant retinal view was graded. Surgical maneuvers then were performed to decrease the condensation. These maneuvers included wiping the IOL surface with a soft-tipped cannula and coating it with viscoelastic. RESULTS: No condensation occurred on IOLs in eyes with an intact posterior capsule. Significantly more condensation occurred on IOLs in eyes with a capsulotomy, regardless of IOL type (P < 0.014). Wiping the condensation resulted in significantly less condensation and improved retinal view on the PMMA and acrylic IOLs when compared with the silicone IOLs (P < 0.024). Condensation was eliminated on all three IOL types after viscoelastic was applied. However, increased distortion of the retinal view was induced by the viscoelastic on the silicone IOL as compared with the other IOLs. CONCLUSIONS: Condensation and subsequent retinal image degradation occurs uniformly after vitrectomy, posterior capsulotomy, and fluid-air exchange in eyes with PMMA, acrylic, and silicone IOLs. Because the condensation can be eliminated most easily on acrylic IOLs compared with silicone IOLs, when foldable IOL techniques are used it is likely that an acrylic polymer IOL would be advantageous for those patients at risk for future vitreous procedures requiring fluid-air exchange.

Animals↗
PubMed1996

Current status of trade in cultured shrimps.

Shrimp culture is an attractive sector of aquaculture business, in view of the high profits and quick turnover. The vast majority of cultured shrimp production occurs in Asian countries. The author details the levels of production, consumption and trade of cultured shrimps since 1991 in and between the major producing countries. A decline in production has been registered in some countries in recent years, due to mass mortality caused by a number of diseases (particularly 'white spot' disease). Efforts to overcome these problems have met with only partial success.

Animals↗
PubMed1995

Monoclonal antibodies for the rapid diagnosis of influenza-B virus infections by ELISA: production and characterization.

BACKGROUND: Monoclonal antibodies directed against conserved epitopes of viral proteins have substantially improved the accuracy of several immunochemical methods in diagnostic virology. OBJECTIVES: To characterize mouse monoclonal antibodies directed against structural protein antigens of influenza-B virus and evaluate their use as diagnostic reagents for the direct detection of such antigens in clinical specimens from patients with respiratory infections of unknown aetiology. STUDY DESIGN: (a) Production and characterization of monoclonal antibodies against influenza-B viral antigens, and (b) their use in two different ELISA systems for detecting influenza-B antigen either directly in clinical specimens or after confirmation by rapid culture in MDCK cells. RESULTS: Four monoclonal antibodies were selected for their specificity for the nucleoprotein antigen as demonstrated by Western blot analysis. The specificity of these antibodies for different epitopes of the nucleoprotein was demonstrated by competition experiments, using unlabelled and biotin-labelled purified antibodies in a sandwich assay. All four antibodies belong to the mouse IgG(2a) isotype, lack haemagglutination inhibition and neutralization properties and exhibit titres as high as 10(-6) in ELISA with as little as 30 ng purified influenza-B virus. ELISA methods using these antibodies detected only influenza-B viral antigens in direct testing of clinical specimens from patients with known influenza-B or influenza-A infections, or after reisolating virus from such specimens in tissue culture of MDCK cells. CONCLUSION: The antibodies were suitable for the direct detection and typing of influenza-B virus in clinical specimens or for use in rapid confirmation cultures.

Journal Article↗
PubMed1995

[Survey of disease of cultural shrimp in Taiwan].

The large number of hemocytes infiltrated several abnormal tissues of kuruma shrimp (Penaeus japonicus), including musculature, hepatopancreas, lymphoid organ, gill filament and sponge tissue. In addition, there were many denatured hemocytes existing inside acidophilic particles and forming granules. Futhermore, in hepatopancreas of kuruma shrimp, a white spot baculovirus (WSBV; 40-50 x 50-300 nm) was discovered in UH (undifferential haemocyte). The epithelium cells, which including stomach cuticle and underlying epidermis of exoskeletal cuticle, could also be infected by WSBV in another main cultural species--grass shrimp (P. monodon). During a period of high water temperature, with pond shrimp in normal condition, the CFU/ml of water bacteria rose from 10(5) to 10(7), but this number had decreased to 10(5) CFU/ml by the time moribund shrimp began to appear. Coincidentally, the total bacterial number isolated from hepatopancreas and musculature of moribound shrimp was over 10(5) (CFU/g) and 10(3)-10(5), respectively. The fauna of bacteria was taken over by the active metabolitic species which were represented by Vibrio species causing the pond shrimp to undergo either behavioral changes, such as swimming on the water surface, or histological changes, such as having whitish muscle color, hemocyte infiltration and granuloma formation etc. Pathogenetic species of Vibrio including V. parahaemolyticus, V. alginoly ticus V. anguillarum, V. fischery and V. damsela were isolated from those tissues of moribund shrimp. The main pathogens, isolated from musculature and hepatopancreas, were V. parahaemolyticus and V. alginolyticus. On the other hand there, was no bacterium could be isolated from the musculature of healthy shrimp and only a single species of Gram (+) coccus--Micrococcus--was isolated from the tissue of hepatopancreas.

Animals↗
PubMed1993

Purification and amplification of DNA from Penaeus monodon-type baculovirus (MBV).

The purpose of this paper was to purify and amplify the DNA fragment of Penaeus monodon-type baculovirus (MBV). Using 30-50% caesium chloride gradients, MBV virions and occlusion bodies with density parameters of 1.28-1.29 and 1.32-1.33 g/ml, respectively, were purified. Two oligonucleotide primers have been successfully designed and utilized for the amplification of a DNA fragment of MBV. After 35 amplification cycles of the MBV DNA fragment, a large amount of amplified product with an approximate molecular weight of 600 bp was obtained. This is the first successfully published work on the amplification of MBV using the polymerase chain reaction (PCR). Using the same primers, DNA extracted from MBV noninfected P. monodon, P. japonicus, and P. orientalis had a negative PCR response. However, a positive PCR response was obtained from DNA extracted from MBV-infected postlarval P. monodon. DIG-dot blot hybridization technique using PCR product obtained from the present study as a probe further confirmed that the product is originated from a portion of MBV polyhedrin gene. It is also suggested that PCR product may be beneficial for an accurate and early diagnosis of MBV infection in larval shrimp.

Animals↗
PubMed1993

Diterpenoid Alkaloids from Delphinium caeruleum.

A new minor diterpenoid alkaloid, caeruline, was isolated from DELPHINIUM CAERULEUM Jacq. ex Camb. Its structure was elucidated as 1 on the basis of spectral evidence. Along with this new compound, three known diterpenoid alkaloids were also isolated from this plant and identified as tatsiensine, delcosine, and lycoctonine which had not been found in this herb previously.

Journal Article↗
PubMed1993

Indocyanine green videoangiography of choroidal neovascular membrane in age-related macular degeneration.

Fluorescein angiography is the traditional tool for the detection of choroidal neovascularization of age-related macular degeneration. However, some limitations exist which impede its efficacy in the detection of subretinal neovascularization. Indocyanine green videoangiography is a recently developed technique which differs from fluorescein angiography in many ways. We performed indocyanine green videoangiography in 18 eyes with occult choroidal neovascularization, demonstrated by fluorescein angiography. Sixteen of the 18 eyes showed an abnormal vessel loop in the early phase of indocyanine green videoangiography. In the late phase, all 18 eyes had abnormal dye retention around the suspected neovascular area; however, only 12 eyes revealed a distinct border of neovascularization. No side effects, such as nausea, vomiting, or allergic reactions, were noted in our patients. Advantages and drawbacks of indocyanine green videoangiography in comparison with fluorescein angiography are discussed.

Choroid↗