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S N Chen

Publications and source records attributed to S N Chen.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Evaluation of two kinds of enzyme linked immunosorbent assay method for clonorchiasis].

In this present study, adult worm antigen of Clonorchis sinensis and the indirect and double sandwich enzyme linked immunosorbent assay (ELISA) were used to detect the serum antibody of clonorchiasis patients from the endemic area of Miao-Li county. The results of indirect ELISA revealed a good correlation between the egg stool count and IgG strength of patients sera. Focusing on the different immunoglobulin classes in serum, the patient group has significantly higher level than that of control group, and the IgG level was distinguishly higher than the other Igs. The result also showed that the sensitivity and specificity on the detection of IgG for clonorchiasis patient were 83.23% and 100%, respectively. After praziquantel treatment, the antibody titer of patients decreased in accord with the time period, and the decrease rate of antibody titer in patients with moderate infection was more closely related to the time after treatment than those in the other degree infection groups. When double sandwich ELISA method was used to detect serum antibody to C. sinensis in patients with the different parasitic infection, it was shown that antibody levels in patients with clonorchiasis were significantly higher than those in the un-identical parasitic infection patients. Both of the sensitivity and specificity by using this method were 100%. Based on the results of the indirect and double sandwich ELISA methods, it is recommended that uses of the double sandwich ELISA incorporated with the indirect ELISA may give a sufficient results on the epidemiological study of human clonorchiasis. It may also be recommended that double sandwich ELISA method can be used for a mass survey and indirect ELISA method for further detection in the patients with clonorchiasis.

Animals↗
PubMed1991

Immunodiagnosis of angiostrongyliasis with monoclonal antibodies recognizing a circulating antigen of mol. wt 91,000 from Angiostrongylus cantonensis.

In the analysis of excretory-secretory (ES) antigens from infective third-stage larvae (L3) of Angiostrongylus cantonensis, one major component of mol.wt 91,000 was not precipitated by pooled sera of patients with eosinophilic meningoencephalitis. Monoclonal antibodies (Mc Ab) secreted from two hybridoma cell lines, established against somatic antigens of L3, recognized this molecule but with different epitope specificities indicated by an additivity index (A.I.) of 83%. The 2 Mc Ab (TD2 and 3A5) belonged to IgG2a and IgM classes, respectively. Combinations of TD2 and 3A5 were used in a sensitive enzyme-linked fluorescent assay (ELFA) for the immunodiagnosis of human angiostrongyliasis. The double-antibody sandwich ELFA method was applied firstly to sera from experimentally infected rats using either TD2 or 3A5 to coat the assay plates. Two fluorescence unit (F.U.) peaks appeared in sera from infected rats collected 18 and 44 days after infection. Specimens from 35 patients were tested, all cerebrospinal fluids (CSF) and most sera (88%) showed positive reactions and the average F.U. of CSF was greater than that of serum.

Angiostrongylus↗
PubMed1991

Environmental problems of aquaculture in Asia and their solutions.

During the past decade aquaculture has expanded very rapidly in Asia. Extensive, semi-intensive and especially intensive systems are currently in use. These systems require careful management to avoid deterioration of the environment and mass mortality of cultured species. Taking shrimp culture as an example, the author discusses the major environmental factors which affect the health of aquatic species. Solutions to the various problems are also discussed.

Animals↗
PubMed1990

Migratory effects on the body surface of Angiostrongylus cantonensis from subarachnoid space to pulmonary artery in rats.

Juvenile worms of Angiostrongylus cantonensis recovered from subarachnoid spaces and pulmonary arteries of rats, respectively, at 28 days post-infection have been compared with respect to their surface composition, antigenicity of surface proteins and morphological appearance. Quantitative and qualitative differences were shown between surface proteins of these two stages of worms. One major and 6 minor proteins appeared on brain stage worm's surface as assessed by surface-labelling and SDS-PAGE techniques. The same, but more predominant banding pattern, with one additional major protein of Mr 80,000 kDa presented on the lung stage worm's surface. Surface components from both stages were antigenic in permissive rat hosts but refractory in nonpermissive human hosts. The surface antigens are common to both stages within the rat. Observed by scanning electron microscopy, the surface appearance of brain stage worms is thickened, rough and irregular. Besides, particle clusters adhere randomly, without cluster adherence but transverse and longitudinal clefts were shown on the surface, before the outer layer was shed. The possible mechanisms of evasion from the host's immune attack with the surface-shedding phenomenon remain to be elucidated.

Angiostrongylus↗
PubMed1989

HLA association of anti-IgA antibody production.

We have HLA typed 46 unrelated IgA deficient blood donors in our region. A weak association to DR3 (RR = 2.07) was observed. However, owing to the heterogeneous nature of this group, we found DR7 may be associated with those who developed class-specific anti-IgA antibodies (RR = 2.94), whereas DR1 may be associated with those who did not (RR = 2.42).

Antibodies, Anti-Idiotypic↗
PubMed1989

A preliminary study of clinical staging in clonorchiasis.

Antibody responses to infection with metacercaria of Clonorchis sinensis were studied in triplet cats. Elevated IgM antibody first appeared seven days after infection, followed by elevation of IgA and IgG. The peak titers of IgM and IgA antibodies were found at 3 weeks and 11 weeks, respectively. IgG antibody was elevated at 3 weeks and reached a peak, then a plateau at 13 weeks. Duration of antibody detection after infection was 1 week to 5 weeks for IgM, and 2 weeks to 28 weeks for IgA. IgM and IgA antibody titers decreased to normal level spontaneously without significant effect by the treatment. Using the animal model, the three clinical stages were classified according to the antibody patterns: i.e. acute stage, IgM(+) IgA(+) IgG(+); subacute stage, IgM(-) IgA(+) IgG(+); Chronic stage, IgM(-) IgA(-) IgG(+). Of 77 human patients with clonorchiasis, there were 3 (3.9%) patients who had subacute infection and 74 (96.1%) patients were in chronic stage.

Animals↗
PubMed1988

Morphology of interleukin-2-stimulated human peripheral blood mononuclear effector cells killing glioma-derived tumor cells in vitro.

This is the first morphological study of interleukin-2-stimulated human peripheral blood mononuclear (PBM) cells resulting in lymphokine-activated killer (LAK) cell activity against human glioma-derived tumor cells in vitro, in which high-resolution differential interference video light microscopy, scanning electron microscopy, and transmission electron microscopy were used. A subset of cells within the LAK cell population are the effector cells and have an asymmetric cellular architecture characteristic of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Upon binding to target cells, the LAK effector cell nucleus is positioned away from the target cell, whereas the granules, Golgi apparatus, and microtubules orient toward the target cell. These LAK-glioma cell conjugates form very tight plasma membrane bonds with numerous interdigitations, and vesicles were found in the small extracellular spaces between the cells. This morphology was not observed in unstimulated PBM-glioma cell co-cultures. Glioma-derived cells react to LAK effector cells by blebbing, becoming round, and rapidly detaching from the substrate. The injured glioma-derived cells had a highly condensed cytoplasm and chromatin, lobular nucleus, and severe plasma membrane blebs, which are consistent with an apoptotic rather than an osmotic lysis mechanism of cell death. This study provides morphological evidence that supports a common cytotoxic mechanism for CTLs, NK cells, and LAK effector cells. The cytotoxic mechanism is based on the local exocytosis of vesicles by the effector cell into the small extracellular space between the effector-target cell conjugate. Granules found in CTLs, NK cells, and LAK cells contain a pore-forming protein that inserts holes in the target cell's plasma membrane through which a lethal substance(s) not yet identified is thought to enter the cell.

Cell Line↗
PubMed1988

Immunodiagnosis of clonorchiasis by enzyme-linked immunosorbent assay.

The present study applied the indirect enzyme-linked immunosorbent assay (ELISA) technique in the immunodiagnosis of clonorchiasis. Antigen used in this study was extracted from adult worms of Clonorchis sinensis obtained from cats. 132 patients with clonorchiasis, 100 healthy persons and 14 patients with other parasitic infections were studied. Mean O.D. ratio with standard deviation of clonorchiasis was 1.41 +/- 0.21 with 0.95 +/- 0.13 of healthy persons. Results revealed 90.2% to 95.5% of sensitivity and 84% to 99% specificity dependent on the two cut off values of O.D. ratio, i.e. 1.10 and 1.20. Antibody titers derived from O.D. ratio highly correlated with direct titration (Y = 0.0303 +/- 1.1766 X, r = 0.8945). Cross reactions of other parasite infections to clonorchiasis were observed in patients with angiostrongyliasis and schistosomiasis.

Animals↗
PubMed1987

Establishment of a cell line derived from top-minnow (Gambusia patruelis).

A cell line, derived from top-minnow (Gambusia patruelis), has been transferred for 114 times in Leibovitz L-15 medium plus 10% FCS (GM-L-15) at a temperature of 31 degrees C and designated as TM. The results of a chromosome analysis of 100 cells at the metaphase stage, show a bimodal distribution of the chromosome number ranged from 21 to 68 with a modal number of 38. At a low seeding density, the plating efficiency of TM cells was 11-12.4%. TM cells are susceptible to EVE, EVA, EVEX, IPNV and LV-1 at 18 degrees C. The result of a sterility test showed that the TM cell line was free of bacterial, fungal and mycoplasmic contamination. The presence of numerous microvilli on the surface of TM cells in the micrographs of normal TM cell. The microvilli are replaced by blebs at the late stage of cytokinesis of the cells.

Animals↗
PubMed1987

Evaluation of enzyme-linked immunosorbent assay for immunodiagnosis of clonorchiasis.

Two groups of patients with parasitologically proved clonorchiasis were recruited from among staff and workers of China Petroleum Company at Miao-Li county. There were 86 patients in the pre-treatment group and 143 patients in post-treatment. The latter were defined as those treated for 18 months after a daily dosage of 3 X 25 mg/kg BW/day of praziquantel. Indirect ELISA was performed to detect the serum antibody against Clonorchis sinensis with extracted crude antigen of adult worms obtained from the bile duct of cats. Direct smears of stool for Clonorchis ova were checked concomitantly. Results revealed significant decrease of optical density ratio between pre- and post-treatment groups. Positive ELISA was detected in 79 pre-treatment group patients (91.8%) and in 28 patients (20.7%) of the post-treatment group (p less than 0.01). Distribution of ELISA titers was shown in patients of post-treatment group towards negative from 400 dilution positive in pre-treatment group. One fourth of the post-treatment group patients with positive ELISA still presented Clonorchis ova in their stool. The main cause was non-compliance of medication. The study confirms the value of immunodiagnosis of C. sinensis by ELISA in the field treatment of clonorchiasis.

Animals↗
PubMed1986

Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Angiostrongylus cantonensis.

The enzyme-linked immunosorbent assay (ELISA) was employed for the sero-diagnosis of Angiostrongylus cantonensis infections in rats and man. Metabolic and 'purified' antigens of adult or juvenile A. cantonensis were evaluated by ELISA and compared against Toxocara canis antigen for sensitivity and specificity. Sera and cerebrospinal fluid (CSF) from both rats and man gave higher ELISA values against antigens of A. cantonensis than those obtained from negative control samples. The results showed that cross reaction occurred between T. canis and A. cantonensis. Of four A. cantonensis antigens tested, a Sephacryl S-300 'purified' fraction was shown to be superior in the ELISA to determine angiostrongyliasis.

Angiostrongylus↗
PubMed1986

HLA and IgA deficiency in blood donors.

We have identified 67 IgA deficient healthy blood donors in our region by systematic screening of 24,782 blood samples. HLA typing results on 36 of these donors indicated a significant association with both HLA-A1 and HLA-B14 antigens. The frequency of A29 and B8 antigens was also increased. However, B8 association may be secondarily involved due to linkage disequilibrium (e.g., A1-B8-DR3). The frequency of HLA-A1 and HLA-B8 antigens was increased in the group of IgA deficient donors who developed anti-IgA antibodies (53.9%) compared to those who did not (26.1%). Although the sample size appears to be too small to show a statistical significance (chi 2 = 2.76, 0.05 less than p less than 0.1), this is the first report to imply a possible HLA association with anti-IgA antibody formation by IgA deficient healthy individuals.

Agammaglobulinemia↗
PubMed1983

Monoclonal antibodies against five structural components of measles virus. I. Characterization of antigenic determinants on nine strains of measles virus.

Monoclonal antibodies against five structural proteins of measles virus were used to determine the degree of antigenic variation within these proteins amongst nine strains of measles virus (four fresh wild-type isolates, two vaccine and two laboratory strains, and a strain derived from a case of subacute sclerosing panencephalitis) giving lytic infections in cell culture. The major surface proteins showed limited variations in their epitopes between the nine strains. No variations in the fusion (F) protein and only three variations in the hemagglutinin (H) protein epitopes were detected by radioimmune precipitation assay and other serological tests using a panel of 11 monoclonal antibodies against each protein. These antibody panels consisted of at least nine and six different binding groups for the H and F proteins, respectively. The two innermost proteins, the nucleocapsid and polymerase proteins, also appeared to be antigenically stable as no variation was detected between strains using in each case a panel of six hybridomas. In sharp contrast, the epitopes on the matrix (M) protein of different strains showed extensive variation in their reactivity with the nine anti-M monoclonal antibodies. The possible use of M protein epitopic markers in classification of measles virus strains is discussed.

Antibodies, Monoclonal↗
PubMed1982

Five measles virus antigens demonstrated by use of mouse hybridoma antibodies in productively infected tissue culture cells.

Mouse hybridoma antibodies against 5 different structural components of measles virus were used in immune fluorescence tests to characterize the appearance of viral antigens in productively infected cell cultures. The antibodies employed in the tests reacted specifically with the hemagglutinin (H, 79K), polymerase (P, 72K), nucleocapsid (NP, 60K) hemolysin-fusion factor (F, 41+20K) and matrix (M, 36K) proteins. Syncytia formed in lytically infected cultures and single isolated cells in persistenly infected cell cultures were both examined. Antibodies against NP and P proteins stained cytoplasmic inclusions varying in size from small dots to more confluent masses, frequently in a perinuclear position. Nuclei of infected cells contained exclusively NP antigen. Antibodies to envelope components--H, F and M--stained cytoplasmic membrane structures and also gave a granular cytoplasmic staining, especially in syncytia. Although all persistently infected cells produced NP antigen and the associated P component, they had a restricted capacity to produce demonstrable amount of envelope antigens. The occurrence of cells containing envelope antigens varied between about 50 and 5 per cent with H and F antigens giving the highest and lowest frequence values, respectively. It is proposed that a restricted capacity of cells to produce biologically active fusion protein is a prerequisite for maintaining a persistent infection in actively dividing cells in vitro.

Animals↗