Search PubMed⌕ Search

Biomedical subjects

P Sun

Publications and source records attributed to P Sun.

At least 91 records · Page 5Linked to original sources
PubMed1992

Targeting of "T" lymphocytes against human hepatoma cells by a bispecific monoclonal antibody: role of different lymphocyte subsets.

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4-8+ TCR alpha/beta+ and CD3+4-8-TCR gamma/delta+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4 + 8-TCR alpha/beta+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-alpha) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.

Antibodies, Monoclonal↗
PubMed1992

Developmental expression of glial fibrillary acidic protein and actin-encoding messages in quaking and control mice.

Quaking is a neurological mutation leading to pleiotropic phenotypic expression, the most prominent being disturbed myelin formation in the central nervous system (CNS) with minor abnormalities in the peripheral nervous system. Previous immunochemical measurements of glial fibrillary acidic protein (GFAP) revealed a marked increase in the protein in several areas of the CNS. To further characterize the regulation parameters of GFAP synthesis, we analyzed the levels of GFAP mRNA in 5 regions of the CNS, some with elevated levels of GFAP and some without. This was compared to the developmental expression of GFAP transcripts in the same regions in normal mice. To establish the specificity of the variations observed with this astroglial specific message, we conducted a similar investigation with actin RNA which is expressed by several cell types in the CNS. Both the actin and the GFAP message were found to be increased in the adult mutant throughout the CNS. In 2-year-old normal mice the messengers for both cytoskeleton proteins were expressed in a higher amount than in young adults.

Actins↗
PubMed1992

Phosphorylation of cyclic adenosine 3',5'-monophosphate (cAMP) response element-binding protein isoforms by the cAMP-dependent protein kinase.

The cAMP response element-binding protein (CREB) mediates transcriptional activation of genes in response to the cAMP signal transduction pathway. There are two different isoforms of CREB, which are generated by alternative RNA splicing. There is evidence that the two isoforms may have different biological activities. As the longer isoform (CREB341) contains a potential phosphorylation site that is not present in the shorter isoform (CREB327), we examined the possible differential phosphorylation of the two CREB isoforms. Recombinant CREB was prepared and used as substrate for phosphorylation by the cAMP-dependent protein kinase in vitro. Phosphopeptide mapping and mutagenesis studies demonstrated that CREB341 contains two sites, serine 133 and serine 98, that can be phosphorylated in vitro by the catalytic subunit of the cAMP-dependent protein kinase. In contrast, CREB327 contains only a single phosphorylation site at serine 119 (equivalent position to serine 133 in CREB341). A kinase titration experiment demonstrated that serine 98 of CREB341 was phosphorylated only at relatively high concentrations of the cAMP-dependent protein kinase. Transient transfection studies were used to test for any possible function of the phosphorylation of serine 98 of CREB341. These studies used GAL4-CREB fusion proteins. We found that mutation of serine 98 to alanine (which would block phosphorylation) has little or no effect on the ability of the CREB fusion protein to activate transcription. These findings suggest that differences in the biological activity of the two CREB isoforms are probably not mediated by differential phosphorylation by the cAMP-dependent protein kinase.

Amino Acid Sequence↗
PubMed1992

[Comparison between of acupuncture and epidural anesthesia in appendectomy].

It was a clinic comparative observation of the effects between acupuncture and epidural anesthesia in appendectomy. Eighty patients with appendicitis were randomly divided into two groups, each of 40 Patients. The results were no significant difference between two groups in successful rate. It is convinced that acupuncture on Zusanli points (ST36) has analgesia. There were less respiratory depression, hypotension, cardiac arrhythmia and less amount of liquid infusion needed than that of the epidural block during operation. Furthermore, in the group of acupuncture anesthesia, the intestinal gas excreted earlier, the analgetics and antibiotics administered were less and the rate of the wound infection were reduced after operation. These postoperative effects were significantly better than the controls. As it is of clear-cut effects of anesthesia by acupuncture with main points Zusanli and auxiliary points Hegu (LI4) and less interfered life sign in the operation, thus it is desirable to use acupuncture anesthesia in appendectomy.

Acupuncture Analgesia↗
PubMed1992

Purification and characterization of N-acetyl-alpha-D-galactosaminidase from Gallus domesticus.

Exoglycosidases modify carbohydrate epitopes on glycoproteins and glycolipids. The N-acetyl-alpha-D-galactosaminidase from the domestic chicken, Gallus domesticus, is an important exoglycosidase which degrades the human blood group A epitope. This enzyme has never been demonstrably purified or thoroughly characterized. We have developed a technique to purify this enzyme to homogeneity. The isolated enzyme has a molecular weight of 49.1 kDa by SDS PAGE and 145.0 kDa by gel filtration. The enzyme is highly selective for PNP-N-acetyl-alpha-D-galactosaminide and is inactive against other low molecular weight substrates. The enzyme hydrolyzes the terminal N-acetyl-alpha-D-galactosaminide residues from blood group A2 erythrocytes. Protease activity is below detectable limits. The enzyme has a pH optima of 3.7, a pI of 8.15, is relatively unaffected by ionic strength, and is stable at 4 degrees C.

ABO Blood-Group System↗
PubMed1991

Purification and characterization of a Coffea canephora alpha-D-galactosidase isozyme.

Exoglycosidases modify carbohydrate epitopes on glycoproteins and glycolipids. The alpha-D-galactosidase from Coffea canephora is an important exoglycosidase which degrades the human blood group B epitope. Although multiple isozymes have been described, they have never been demonstrably purified and thoroughly characterized. We have developed a technique to purify an isozyme to homogeneity. The isolated enzyme has a molecular weight of 36.7 kDa by SDS PAGE and 34.0 kDa by gel filtration. The isozyme is highly selective for alpha-D-galactosides and inactive against other low molecular weight substrates. It hydrolyzes the the terminal alpha-D-galactosyl residue from the blood group B epitope. Protease activity is below detectable limits. The isozyme has a broad pH optima at 6.3, a pl of 7.03, is unaffected by ionic strength, and is stable at 4 degrees C.

Amino Acids↗
PubMed1991

[The in vitro induction of antibody responses of human lymphocytes and its application to hybridoma production].

Sources of immunized lymphocytes constitute one of the main obstacles in the production of human monoclonal antibodies. We tried to get them through in vitro immunization. Cells from excised tonsils or trauma spleens were used for the induction of antibody responses in vitro. Antibodies to different antigens including sheep red blood cells, ovalbumin, tetanus toxoid, and hepatitis B surface antigens were induced in 7-14 days' cultures. Taking tetanus toxoid as antigen, we analysed the various factors required for antibody induction with statistics analysis, which included cell separation method, T cell conditioned medium, antigen dosage, serum content, and concentration of mitogen PWM and LPS. The results showed: (1) The cell separation method influenced the antibody production significantly in comparison with other factors. It signified that immune cells' combination was the most influential factor. (2) Serum also constituted quite important influencing factor especially in the later period of culture. However, it did not make much differences if it attended 10% or so. The antigens and mitogens tended to be used at low concentration. (3) Due to the significant variation among individuals and among different antigens, it is suggested to set up the culture system with some flexibility so as to adapt to the variation in cells and antigens from different sources. The present culture system we use includes nylon wall column separation of cells, suitable range of antigens (three doses instead of one), and either 10% T cell conditioned medium or a mixture of 1 microgram PWM/ ml + 0.1 microgram LPS/ml. The human B lymphocytes stimulated in vitro with tetanus toxoid were used for the construction of human hybridomas.

Animals↗
PubMed1989

Effects of vigabatrin and of GABA on myelinated rat cerebellar cultures: preliminary data.

1. The aim of this study was to evaluate the effect of high concentrations of vigabatrin (gamma-vinyl GABA) and of GABA on myelin of the central nervous system cultures. 2. Explants of rat cerebellum were cultured for 14-19 days in vitro on collagen-coated coverslips in Leighton tubes. They were exposed for up to 14 days to 500 nmol ml-1 vigabatrin or to 1000 nmol ml-1 GABA. 3. Qualitative and quantitative blind examination of living cultures and of Sudan black B-stained slides showed mild toxicity of both drugs for myelinated fibres. No clear-cut differences could be demonstrated between the two compounds, although vigabatrin seemed slightly more toxic than GABA at these doses. 4. In electron microscopy, no patent intramyelinic oedema nor primary demyelination were seen. On the contrary, some degenerating myelinated fibres and astrocytic gliosis were seen in both experimental conditions. The changes involved axons as well as myelin sheaths. 5. The toxicity of GABA and vigabatrin was surprisingly mild in this very sensitive model.

Aminocaproates↗
PubMed1988

Sperm antibodies induced by anti-idiotype antibodies: a strategy in development of immunocontraceptive vaccines.

The potential of using anti-idiotype antibodies as immunocontraceptive vaccines is evaluated in this study. Two sperm monoclonal antibodies, HS 63 and MS 204, which have significant inhibitory effect on the in vitro and in vivo fertilization of mouse were selected to elicit heterologous anti-idiotype antibodies. Rabbit antisera against HS 63 or MS 204 were collected after the third immunization. After the removal of anti-Fc fragments with an irrelevant mouse IgG immunoadsorbent column, anti-idiotype antibodies (anti-Id HS 63 or anti-Id MS 204) were purified from the antisera with affinity chromatography. HS 63 or MS 204 was used as respective ligand. The purified anti-idiotype antibodies conjugated with hemocyanin were used to immunize female CD-1 mice as the experimental group. Another group of female CD-1 mice were immunized with adjuvant only as the control group. Each group had three mice. The immune responses varied significantly among individual mice. The antisera could stain the acrosomal region of sperm in the indirect immunofluorescent assay in a way which is similar to the original monoclonal antibodies (HS 63 and MS 204). The inhibitory effect of antisera on the sperm fertilization of mouse oocytes in vitro was significant in both cases. In the case of antisera against anti-Id HS 63, the control group showed 81.8% and 49.3% of fertilization rates, whereas the corresponding rates of the experimental group were only 35.7% and 20.5%, respectively. Similarly, for antisera against anti-Id MS 204, the experimental group also revealed lower fertilization rates as compared with those of the controls (50.0% vs. 95.8% and 36.8% and 81.3%). The results of this study suggest that anti-idiotype antibodies against HS 63 and MS 204 contain the internal image of the sperm antigen and they could elicit an immune response with a significant antifertility effect. Therefore, they might not only be contributory to further study and understanding of the original antigens in structure and function but also be used as an alternative in the development of immunocontraceptive vaccines.

Animals↗
PubMed1987

Sex difference of antifertility effect by passively immunized monoclonal sperm antibodies.

Sperm-specific monoclonal antibodies (MS 204, MS 207, HS 11, and HS 63) that had been shown to inhibit fertilization of mouse oocytes in vitro were used to passively immunize male and female mice. In vitro and in vivo fertilization experiments were performed to compare the efficacy of resulting antifertility effects owing to the presence of circulating sperm antibodies. When the sperm from the antibody-treated mice were recovered for insemination, a partial inhibition of fertilization of mouse oocytes in vitro was observed. However, under the same antibody dose that effectively inhibits the in vivo fertilization of treated female mice the fertilization rate of the treated male was not significantly reduced, when they were mated with normal superovulated females followed by in vitro embryo culture. Similarly, on day 9 after mating with the antibody-treated males, the number of fetuses in mated females was not significantly different from that of the control. In contrast, when the antibody-treated females were mated with the proven fertile males, the number of fetuses was significantly reduced in response to the antibody treatment. When I-125-labeled monoclonal sperm antibodies were used to passively immunize male mice, the percentage of antibodies recovered from epididymis (relative to that of blood) was not much different from that of other organs, except for lower percentages detected in brain and testis. In treated females, oviduct and uterus revealed the presence of relatively high percentages of antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Spermicidal effect in vitro by the active principle of garlic.

The in vitro spermicidal effect of Allitridum, an active principle of garlic, was investigated. The data showed that sperm motility was inhibited with various concentrations of Allitridum at different intervals ranging from 20 seconds-200 minutes as compared to control. An obvious immobilization of spermatozoa occurred at 7.5 mg/ml of Allitridum. The effects on sperm motility appeared to be dose-dependent.

Allyl Compounds↗
PubMed1985

Vaginal reconstruction using labia minora flaps in congenital total absence.

A simplified technique using labia minora for total lining of the neovagina succeeded in 7 of our 10 patients with encouraging cosmetic and physiological results. In the remaining 3 patients, because of the smaller size of the labia minora, additional free skin grafts were necessary. The surgical technique, especially the surgical anatomy of the labia minora, is described in detail.

Adult↗