Biomedical subjects
Publications and source records attributed to S Feng.
A new kinetic fluorimetric method for the determination of trace oxalate is described. The method is based on the enhancing effect of oxalate on the oxidation of butyl rhodamine B by potassium dichromate in the solution of hydrochloric acid. The linear range of the determination is 1.20-10.0 micrograms.mL-1. This method has been used to determine trace oxalate in spinach with satisfactory results.
COP9 complex is one of the most important components that act in repressing photomorphogenesis in Arabidopsis thaliana. FUS6 has been identified as one of eight subunits of the COP9 complex in Arabidopsis. Using Arabidopsis Fus6 cDNA as a probe, we screened a rice root cDNA library and a rice genomic library. A 1730-bp cDNA was obtained, which has an open reading frame corresponding to 441-amino-acid. This 441 amino acids putative protein has 67% identity with Arabidopsis COP11/FUS6 (AtFUS6) and 40% identity with human GPS1, an AtFUS6 orthologue. So we designated this novel gene as rFUS6. The 6.2-kb genomic sequence of rFUS6 was also obtained. Sequence comparison showed that the rFUS6 gene had six exons and five introns. Sequence inspection of the 5'-flanking region revealed the presence of some potential light-regulated cis-elements such as a G-box, GT-1 binding sites, and a TGACG motif. Southern hybridization with rice total DNA showed that rFUS6 was perhaps a single copy gene. The rFUS6 locus was mapped by hybridization with a rice BAC library membrane and the results showed that rFUS6 had a locus at 16.3 cM of chromosome 1.
A multicompartment electrolyzer, which has been used for preparative electrophoresis [Z. Liu, Z. Huang, J.-Y. Cong, et al., Sep. Sci. Technol. 31 (1996) 427], is applied for carrying out affinity chromatography in an alternating electric field. The effect of electric field strength on the adsorption and desorption characteristics is experimentally examined with human serum albumin and Blue Sepharose Fast Flow as a model system. It is shown that the existence of an electric field leads to a significant change in the adsorption capacity of the blue dye, which may be used for establishing a preferential adsorption to achieve a high resolution. The adsorption speed increases slightly with respect to the increase of electric field strength, while adsorption capacity in the presence of an electric field is independent of the electric field strength. Different elution behavior is observed as function of adsorption condition and a high recovery of the adsorbed protein is obtained when the adsorption is carried out in the presence of an electric field.
BACKGROUND: Systemic administration of the inhibitor of costimulation, CTLA4Ig, has been shown to prolong islet graft survival. The purpose of this study was to compare local and systemic expression of murine CTLA4Ig in transplants of rat islets into mice. METHODS: Murine CTLA4Ig was made by joining two polymerase chain reaction products, the extracellular portion of CTLA4 and the Fc portion of IgG2a. Recombinant adenovirus expressing CTLA4Ig (AdCTLA4Ig) was generated using the strategy of Cre-lox recombination. Isolated rat islets infected with AdCTLA4Ig at multiplicities of infection (MOIs) ranging from 0.1 to 10 were transplanted into streptozocin diabetic male B6AF1 mice. Control islets were mock infected or infected with AdLacZ or AdsIg, a recombinant adenovirus expressing only the Fc portion of IgG2a. Also, AdCTLA4Ig and control viruses were injected intramuscularly into mouse transplant recipients at the time of islet transplantation to provide CTLA4Ig systemically. RESULTS: Control islets transplanted into diabetic mice were rejected in 13-17 days. Islets infected with AdCTLA4Ig had dose-dependent prolongation of graft survival. Prolonged survival was even found with very low MOIs of 0.1 and 0.5, with survivals of 24+/-4.2 and 25+/-2.2 days, respectively. Survival with an MOI of 10 was 39+/-8.7 days. With intramuscular injection, no prolongation was found at the lowest relative MOIs of 0.2 and 1, but there was dose-dependent prolongation of graft survival with larger doses. At the highest relative MOI of 400, survival was prolonged to 58+/-10 days. CONCLUSIONS: Rat islets infected with AdCTLA4Ig transplanted into mice had prolonged graft survival. Prolonged survival with MOIs as low as 0.1 and 0.5 indicates that only a minority of islet cells need to express CTLA4Ig to exert an effect. Moreover, the results suggest that the improved islet graft survival is due to a local influence of CTLA4Ig.
The glycoprotein (Gp) Ib/IX complex contains three transmembranous leucine-rich repeat polypeptides (GpIbalpha, GpIbbeta, and GpIX) that form the platelet von Willebrand factor (vWF) receptor. GpIb/IX functions to effect platelet adhesion, activation, and aggregation under conditions of high shear stress. GpIb/IX is expressed late in the ontogeny of megakaryocytes, the precursor cell that releases platelets when it reaches its terminal stage of differentiation. Because signal pathways can be reused at different stages of development by integration with different effector pathways and because cellular adhesion through other receptor families often modulates cell growth, the hypothesis that GpIb/IX regulates cell growth was investigated. The surface expression of recombinant GpIbalpha decreases the proliferation of transduced CHO cells. GpIbalpha causes growth arrest in the G1 phase of the cell cycle associated with the induction of the cyclin-dependent kinase inhibitor p21. G1 arrest induced by recombinant GpIbalpha in heterologous cells requires signaling through the 14-3-3zeta binding domain of GpIbalpha and is partially dependent on its engagement by the extracellular ligand vWF. Growth arrest induced by the expression of recombinant GpIb/IX is followed by apoptosis of the transduced cells. The endogenous expression of GpIbalpha in human hematopoietic cells is associated with decreased proliferation. These results suggest that the expression of the GpIb/IX complex regulates megakaryocyte growth.
Core-shell type waterborne polyacrylate-polyurethane microspheres in which polyurethane acts as the shell and acrylic polymer as the core were prepared. Hydroxyethyl acrylate and adipic dihydrazide were used as cross-linking agents introduced to the ends of the shell molecular chains, and two kinds of cross-linked structures between the core and the shell were formed. The photon correlation spectroscopy studies indicate that all the microspheres present continuous particle-size distributions and their mean particle sizes are smaller than 200 nm. The transmission electron photographs reveal that there are obvious core-shell structures for the noncross-linked type microsphere particles and different cross-linked networks between the core and shell for the two kinds of cross-linked type microsphere particles. These microspheres possess excellent storage stability, water resistance, and coating properties. Copyright 1999 Academic Press.
Phylogenetic relationships within the kinetoplastid flagellates were inferred from comparisons of small-subunit ribosomal RNA gene sequences. These included three new gene sequences from Cryptobia bullocki, (2091 bp), Cryptobia catostomi (2090 bp), and Cryptobia salmositica (2091 bp). Trees produced using maximum parsimony and distance-matrix methods (least squares and neighbor-joining) demonstrated with strong bootstrap support, that the kinetoplastids are a monophyletic group divided into two major lineages consistent with the two suborders, Trypanosomatina and Bodonina. Within the trypanosomatid clade, the genus Trypanosoma is a monophyletic group that divides into two groups, the salivarian trypanosomes and the stercorarian trypanosomes. Dimastigella and Rhynchobodo, currently classified in the Bodonina, are basal to the trypanosomatid-bodonid clade, suggesting that the suborder Bodonina is paraphyletic. Further, Trypanoplasma borreli grouped within the Cryptobia clade, and was more closely related to C. salmositica than to either C. bullocki or C. catostomi. This new molecular evidence, coupled with morphological similarities of the two genera, again calls into question the validity of the genus Trypanoplasma.
A gas chromatographic-mass spectrometric (GC-MS) method was used for the simultaneous analysis of cocaine and its metabolites (norcocaine, benzoylecgonine, norbenzoylecgonine, ecgonine methylester, cocaethylene, and the o-, m, and p-hydroxy derivatives of cocaine and benzoylecgonine) in meconium specimens collected from newborns prenatally exposed to the drug in an effort to determine which of these metabolites are more relevant in the confirmation of immunoassay-positive specimens. Significant metabolites included benzoylecgonine and its m- and p-hydroxy derivatives. Reanalysis of immunoassay-positive meconium specimens that previously failed to confirm by GC-MS for benzoylecgonine revealed that the GC-MS confirmation rate could be substantially enhanced by inclusion of m- and p-hydroxybenzoylecgonine in the analysis along with benzoylecgonine. Several specimens were found to be positive for hydroxylated derivative(s) in the absence of benzoylecgonine itself.
A gas chromatography-mass spectrometry method was developed for the analysis of flunitrazepam (FN) and its major metabolite, 7-amino-flunitrazepam (7-amino-FN), in both plasma and whole blood. The method was based on acid hydrolysis of the samples after dilution with HPLC water followed by extraction and derivatization (heptafluorobutyrate) of the resulting benzophenones. Analysis of plasma and whole blood samples from subjects administered 2-mg doses of FN showed that FN was only detected in whole blood (LOD 5 ng/mL) and not in plasma. However, 7-amino-FN was detected in both plasma and whole blood, although the levels were much higher in plasma. 7-Amino-FN was detected for the entire period of specimen collection (12 h), but FN was only detected in whole blood for 4 h after ingestion with peak levels after 1 h.
In treating children with mongolism (Down's syndrome) with electroacupuncture, the latent period of P3 is shortened, which shows that the cerebral reaction to external stimulus in classification, encoding and recognition is accelerated. Along with the elevated P3 amplitude, the cerebrum is more capable of processing the external information, showing improvement of the mental state.
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OBJECTIVE: To evaluate the killing effect of interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) activated bone marrow cells on K562 cells. METHODS: Semi-solid colony and 3H-TdR incorporating method were used. RESULTS: Bone marrow from leukemia patients in remission was activated in vitro with IL-2 for 3 days. The activated bone marrow (ABM) displayed killing effects of 0.31-2.30 logs on K562 cells. This killing effect was further increased to 0.30-3.15 logs when IFN-alpha added with IL-2 to the marrow for activation. IL-2 alone or in combination with IFN-alpha showed no inhibition of CFU-GM and K562 cells. Compared with IL-2 or IFN-alpha alone, the combination of the two cytokines could more effectively maintain the killing effect of ABM on leukemic cells. CONCLUSIONS: IFN-alpha can augment the purging effect of IL-2 ABM and combination of the two cytokines can effectively maintain the cytotoxicity of ABM.
In the pre - Qin literature, the characters "ti", "pi", "nian" refer to "tear", "beast skin" and "year" respectively and it became "nasal discharge", "man's skin" and "age" respectively in the Han dynasty, which never appeared in the pre - Qin period. By studying the semantic changes in books of different times, the meanings of the above 3 characters, that frequently occurred in Neijing, are identical with those books of the Han dynasty. Hence, it can be concluded that Neijing can only be completed not early than the Han dynasty.
OBJECTIVE: To investigate the relationship between beta-glucuronidase and tumor differentiation and invasion in human colorectal carcinoma. METHODS: The expression of beta-glucuronidase in human colorectal carcinoma tissue was determined by streptavidin-peroxidase immunohistochemical method. Four human colorectal carcinoma cell lines were analysed for beta-glucuronidase in the medium by spectrophotometry method. RESULTS: Compared with well differentiated colorectal carcinomas, beta-glucuronidase expression was higher in poorly differentiated tumors. An association was found between beta-glucuronidase overexpression in colorectal carcinoma and more advanced tumor Dukes' stage (P < 0.05). With increasing maximum depth of invasion, tumors more frequently show higher beta-glucuronidase expression (P < 0.05). The analysis of colorectal carcinoma cell lines for beta-glucuronidase showed that low levels of beta-glucuronidase (activity range, 1.29 to 1.96 micrograms/10(6) cells per hour) were associated with the well differentiated cell lines which have low invasiveness (CX1, CCL187), and this was in contrast to the elevated level of the enzyme (2.46 to 2.73 micrograms/10(6) cells per hour) present in the medium derived from the poorly differentiated cells with high invasiveness (CCLI227, CCL228) (P < 0.05). CONCLUSIONS: Poorly differentiated human colorectal carcinoma cells could synthesize more beta-glucuronidase, enhance local invasion. Immunohistochemical staining for beta-glucuronidase might be helpful to diagnosing the differentiation degree and invasiveness of human colorectal carcinomas, and the secreted beta-glucuronidase might provide a useful measurement of the differentiation degree and invasiveness of cultured human colorectal carcinoma cells.
OBJECTIVE: To compare the clinical outcome of allogeneic peripheral blood stem cell transplantation(PBSCT) with that of bone marrow transplantation(BMT). METHODS: Twenty-six patients received allo-BMT and 24 received allo-PBSCT in our hospital between August 1991 and September 1998. Conditioning regimens were CY 120 mg/kg plus STBI 9-10 Gy or BU 16 mg/kg or Mel 140-160 mg/m2 plus CY 120 mg/kg. RESULTS: Twenty-three patients of PBSCT and 24 of BMT group engrafted successfully. The median follow-up duration was 352(19-745) days for the PBSCT group and 546(19-2,329) days for the BMT group. Transplant-related death was 4(16.7%) patients in the PBSCT and 7(26.9%) in BMT group (P = 0.38). Three(12.5%) patients in PBSCT and 5(19.2%) in BMT group relapsed(P = 0.27). The 2-year probabilities of disease-free survival(DFS) for PBSCT and BMT group were (67.9 +/- 11.3)% and (57.7 +/- 9.7)%, respectively(P = 0.24). aGVHD occurred in 6(25%) patients in the PBSCT and 6 (23.1%) in the BMT group (P = 0.624), while cGVHD did in 13(56.5%) and 1 (3.85%), respectively (P = 0.0002). CONCLUSION: The clinical outcome of allo-PBSCT is similar to allo-BMT, except for a higher incidence of cGVHD.
OBJECTIVE: To report a case of post-allogeneic peripheral blood stem cell transplantation (allo-PBSCT) pure red cell aplasia(PRCA) and the treatment outcome. METHODS: A patient with acute non-lymphoblastic leukemia(M2a) was treated with allo-PBSCT. His post-PBSCT PRCA was treated with plasmapheresis(2-3 times weekly) and Epo(3,000 U/day, subcutaneously). RESULTS: Reticulocyte count (Ret) recovered to 0.01 at day +131 and hemoglobin reached 110 g/L at day +154. Erythroid cells in the bone marrow recovered to 0.25, and BFU-E and CFU-E within normal range. This normalized hematopoiesis remained for over 5 months after the cessation of Epo. CONCLUSION: Post allo-PBSCT PRCA can be successfully treated with plasma exchange and Epo.
OBJECTIVE: To investigate factors affecting long-term survival in patients with resected gastric cardia cancer. METHODS: Survival was analyzed retrospectively in 584 patients with gastric cardia carcinoma who received tumor resection from 1964 through 1982. RESULTS: The 10-year survival rate was 17.1%. The major factors influencing survival were clinical staging, degree of differentiation, gross tumor type and size (P < 0.05) and status of lymph node metatasis (P < 0.01). Residual tumor at resection edge and tumor thrombi did not significantly affect survival, nor did sex/age, and course of the disease. CONCLUSION: Early detection, early diagnosis and early surgical resection are the key to improve 10-year survival of patients with resected cancer of the gastric cardia. Why residual tumor left at the resection edge and the presence of tumor thrombi do not influence survival needs to be further studied.
OBJECTIVE: The similarities of masticatory muscles and teeth orientations between miniature pigs and human beings were studied in order to evaluate the use of miniature pigs in oral biomechanics research. METHODS: By means of anatomy, the shapes, start-stop points and orientations of muscle of major masticatory muscles of miniature pigs were measured. Inclination of upper and lower teeth long axis was studied with lateral xray film of mandibles. RESULTS: The main masticatory muscles of miniature pigs include masseter muscle, temptory muscle, lateral pterygoid muscle, medial pterygoid muscle and zygomaticomandibular muscle. The angles of masticatory muscles and base plane are 63.9 degrees in massater muscle, 114.55 degrees in temple muscle, 64.4 degrees in medial pterygoidp muscle. The long axises of miniature pigs teeth are 6.1 degrees in the upper first molar, 6.5 degrees in the lower first molar, 7.3 degrees in the upper third premolar, 3.8 degrees in the lower third premolar. CONCLUSION: The masticatory muscles of miniature pigs are similar with human being in the shape, start-stop point and orientation of muscle force. The third premolar and the first molar of miniature pigs inclinate mesially, and are similar with the first premolar and the first molar of the human beings. Miniature pigs can be used as an animal models which can explain some problems of gnathostomatic system of human beings.