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Biomedical subjects

J Feng

Publications and source records attributed to J Feng.

At least 325 records · Page 18Linked to original sources
PubMed1977

Determination of L-ascorbic acid levels in culture medium: concentrations in commercial media and maintenance of levels under conditions of organ culture.

The method of Deutsch and Weeks was modified to provide a reliable and reasonably quick method for assaying the L-ascorbic acid content of culture medium. The modified method was used to determine the decay of L-ascorbic acid under various conditions of culture and the concentration of the vitamin in commercially prepared media. The half-life of L-ascorbic acid in a modified New circulator gassed with 95% O2 + 5% CO2 was 1.5 hr.; and when gassed with 20% O2 + 5% CO2 + 75% N2, about 2 hr. In Petri dishes gassed with 20% O2 + 5% CO2 + 75% N2, the half-life of L-ascorbic acid was 0.9 hr. About 4% of the L-ascorbic acid was lost per day when medium was stored at 0 degrees C and about 9% per day when stored at 5 degrees C. When medium with an initial content of 300 microng per ml was stored at room temperature, the half-life was found to be 15.5 hr. The L-ascorbic acid in five commercially available media, which contain the vitamin in their formulations, was assayed immediately after their delivery to the laboratory. The values of L-ascorbic acid measured in these media were in all cases far lower than prescribed. A continuous-flow organ culture system has been designed which allows the provision of a relatively constant level of L-ascorbic acid to explant by taking advantage of the slow oxidation of L-ascorbic acid at 0 degrees C.

Ascorbic Acid↗
PubMedDate not supplied

Is the endogenous antipyretic neuropeptide alpha-MSH responsible for reduced fever in aged rabbits?

The reduced febrile response in aged man has been noted since the beginning of clinical thermometry. Our previous research on aged rabbits and squirrel monkeys disclosed a similar reduced fever, presumably due to a decrease in central receptors for endogenous pyrogen. However, because central alpha-melanocyte stimulating hormone (MSH) appears to have a potent role in physiological control of fever, it may be that increased release of the peptide is responsible for the reduced febrile response in aged animals. To test this idea, antiserum specific to MSH was administered intracerebroventricularly to rabbits of known age. The antiserum given according to three schedules of treatment augmented fever caused by IV injections of interleukin-1 (IL-1) in young (less than 2 years) male and female rabbits. Aged female rabbits (3-5+ years) and females aged 2-3 years showed significant augmentation of fever only after pretreatment plus acute injection of antiserum. A single ICV injection of MSH (200 ng) reduced fever in all groups with the greatest antipyretic effect in the aged females. The results indicate that while aged rabbits have an increased antipyretic response to central MSH, binding of the endogenous peptide does not result in marked increases in fever in these animals. Thus, whereas a change in central MSH sensitivity may contribute to reduced fever in aged homeotherms, a reduction in central pyrogen receptors appears to be the most parsimonious explanation.

Aging↗
PubMedDate not supplied

Chronic ethanol feeding alters the structure and function of the epidermal growth factor receptor in rat stomach.

We investigated the effect of chronic ethanol feeding on the EGF receptor in rat stomach. Adult male rats were fed either an isocaloric control or ethanol (EtOH)-containing liquid diet (36% total calories as EtOH) for 4 weeks EtOH significantly reduced the specific binding of 125I-EGF to the gastric mucosal membrane (control vs. EtOH, 2.07 +/- 0.2 vs. 0.94 +/- 0.16 fmol/mg protein; p < 0.01). Scatchard analysis suggested that the lower binding might be due to the reduction of EGF receptor number, and/or the affinity of the high-affinity binding site. Western blot analysis, using anti-EGF receptor antibody, revealed four immunoreactive protein bands (180, 150, 60, and 50 kDa) in the lectin-purified gastric membrane prepared from both groups. However, the intensities of these protein bands in the EtOH-fed animals were 90% lower compared to the controls. In the EGF-responsive protein kinase assay, 32P-ATP was incubated with lectin-purified samples in the absence or presence of 1 microM EGF. EGF stimulated autophosphorylation of the EGF receptor (180 kDa) in stomach from the control groups, but not the EtOH-fed animals. This EtOH-related alteration of the gastric EGF receptor may be one of the mechanisms underlying the gastric pathology associated with alcohol abuse.

Animals↗
PubMedDate not supplied

Mutants defective in chromosome partitioning in E. coli.

Recent experimental results suggest that replicated daughter chromosomes (nucleoids) in Escherichia coli move non-progressively and abruptly at an early stage of the D (division) period from midcell toward the cell quarter positions, which will become the centres of the daughter cells. The chromosome positioning at the quarter positions was found to be controlled by the muk gene products. In muk mutants, normal size anucleate cells are spontaneously produced during cell division. The mukA gene is identical to the tolC gene encoding an outer membrane protein. The mukB gene codes for a 177-kDa protein. The amino acid sequence of the MukB protein deduced for the nucleotide sequence suggests that the MukB protein has five characteristic secondary structure domains: an amino-terminal globular domain containing a consensus sequence binding with ATP or another nucleotide. The central region of the protein consists of two alpha-helical coiled-coil domains and one globular domain. A carboxyl-terminal globular domain is rich in cysteine and positively charged residues arginine and lysine. Two MukB protein molecules might form a homodimer in the coiled-coil regions. The predicted secondary structure of the MukB protein suggests that the protein provides the force required for the positioning of nucleoids from midcell toward the cell quarters. The mukC and mukD genes are located at 88 and 41 min of the chromosome map, respectively.

Amino Acid Sequence↗
PubMedDate not supplied

Vascular endothelial growth factor and other biological predictors related to the postoperative survival rate on non-small cell lung cancer.

OBJECTIVE: An analysis of postoperative 1-5 year-survival rates related to vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGF-r), microvascular density (MVD), P53, H-ras, CerbB2, proliferative index (PI), divisional index (DI) were carried out on 127 cases of non-small cell lung cancer (NSCLC) treated with curative resection and aim to find out more sensitive molecular prognostic predictors for the reference of medicine and molecular pathology. METHODS: All the cases were staged strictly using the UICC criteria of 1997 and regional lymphonodes seen by the naked eye should be dissected and sent to pathology with lung specimens. Immunohistochemical analyses were used for those biological predictors. Kaplan-Meier curve, Cox univariance and multivariance analysis were used for the survival and prognostic predictors. RESULTS: 52 cases (40.9%) with high expression of VEGF showed a worse postoperative year-survival rate than cases with low expression, but no statistical difference. The difference of survival on stage I case with high and low expression were closed to be significant value (P=0.0643). P53, PI and DI were related to postoperative survival, P=0.0341, 0.0005 and 0.0162, respectively. Co-expression of VEGF combined with P53, PI and DI was calculated for the difference of year-survival rate by Cox multivariance analysis. The survival rates of cases with both negative VEGF +P53 or VEGF+PI co-expression rate were better than those with both positive or either positive, P values were 0.0159 and 0.0154, respectively. CONCLUSION: The post-operative year-survival of NSCLC was of no statistical difference between with high expression and low expression of VEGF, but in stage I case it was closed to be significant difference, it speculated that the neoangiogenesis is more obviously in early stage NSCLC, but in the later stage of NSCLC, it may be covered by more complicated molecular-biological factors such as P53 and other oncogens. Co-expression of VEGF combined with p53 or PI was more meaningful than a single biological predicator on survival rate of NSCLC, it is worth to do further studies.

Biomarkers, Tumor↗
PubMedDate not supplied

Is the integrate-and-fire model good enough?--a review.

We review some recent results on the behaviour of the integrate-and-fire (IF) model, the FitzHugh-Nagumo (FHN) model, a simplified version of the FHN (IF-FHN) model and the Hodgkin-Huxley (HH) model with correlated inputs. The effect of inhibitory inputs on the model behaviour is also taken into account. Here, inputs exclusively take the form of diffusion approximation and correlated inputs mean correlated synaptic inputs (Sections 2 and 3). It is found that the IF and HH models respond to correlated inputs in totally opposite ways, but the IF-FHN model shows similar behaviour to the HH model. Increasing inhibitory input to single neuronal models, such as the FHN model and the HH model can sometimes increase their firing rates, which we termed inhibition-boosted firing (IBF). Using the IF model and the IF-FHN model, we theoretically explore how and when IBF can happen. The computational complexity of the IF-FHN model is very similar to the conventional IF model, but the former captures some interesting and essential features of biophysical models and could serve as a better model for spiking neuron computation.

Action Potentials↗
PubMedDate not supplied

The experimental study of ovarian carcinoma vaccine modified by human B7-1 and IFN-gamma genes.

With the advance of immunology, immunogene therapy is becoming a possible therapeutic alternative to advanced cancer. The aim of tumor immunogene therapy is to enhance the immune response to tumors. Evidence suggests that CD80 (B7-1) and Interferon-gamma (IFN-gamma) play important roles in antitumor immunity induced by T lymphocyte. To study the antitumor immune effects of ovarian carcinoma vaccine modified with human B7-1 and IFN-gamma genes, we constructed the bicistronic retroviral vector pLXSN, encoding human B7-1 and IFN-gamma. In vitro, the primary ovarian carcinoma cells were transduced with the retroviral vector and prepared as a vaccine. Then autologous lymphocytes were irritated with the ovarian carcinoma cells for competition inhibitory cytotoxic testing. The tumor-specific cytotoxic activity was greatly enhanced by the double gene-modified vaccine. In vivo, the tumorigenicity of the double gene-modified ovarian cell line 3AO/B7-1.IFN-gamma was evaluated in a human immune reconstituted SCID mice (hu-PBL-SCID) model. The double-gene modification markedly decreases tumor genecity. Together, the results suggest that combining B7-1 and IFN-gamma could be a useful therapeutic approach in ovarian cancer.

Animals↗
PubMedDate not supplied

QSAR modeling of datasets with enantioselective compounds using chirality sensitive molecular descriptors.

Shape descriptors used in 3D QSAR studies naturally take into account chirality; however, for flexible and structurally diverse molecules such studies require extensive conformational searching and alignment. QSAR modeling studies of two datasets of fragrance compounds with complex stereochemistry using simple alignment-free chirality sensitive descriptors developed in our laboratories are presented. In the first investigation, 44 alpha-campholenic derivatives with sandalwood odor were represented as derivatives of several common structural templates with substituents numbered according to their relative spatial positions in the molecules. Both molecular and substituent descriptors were used as independent variables in MLR calculations, and the best model was characterized by the training set q2 of 0.79 and external test set r2 of 0.95. In the second study, several types of chirality descriptors were employed in combinatorial QSAR modeling of 98 ambergris fragrance compounds. Among 28 possible combinations of seven types of descriptors and four statistical modeling techniques, k nearest neighbor classification with CoMFA descriptors was initially found to generate the best models with the internal and external accuracies of 76 and 89%, respectively. The same dataset was then studied using novel atom pair chirality descriptors (cAP). The cAP are based on a modified definition of the atomic chirality, in which the seniority of the substituents is defined by their relative partial charge values: higher values correspond to higher seniorities. The resulting models were found to have higher predictive power than those developed with CoMFA descriptors; the best model was characterized by the internal and external accuracies of 82 and 94%, respectively. The success of modeling studies using simple alignment free chirality descriptors discussed in this paper suggests that they should be applied broadly to QSAR studies of many datasets when compound stereochemistry plays an important role in defining their activity.

Ambergris↗
PubMedDate not supplied

Genetic distinctiveness of endangered dwarf blue sheep (Pseudois nayaur schaeferi): evidence from mitochondrial control region and Y-linked ZFY intron sequences.

To elucidate the controversial systematic relationship of blue sheep (Pseudois nayaur) and endangered dwarf blue sheep, we sequenced part of the mtDNA control region and Y-linked ZFY intron, and carried out phylogenetic analyses. Mitochondrial results revealed that the dwarf blue sheep is a strongly supported monophyletic group, with an average of 12.21% sequence divergence from the blue sheep. This is the first genetic evidence for the distinctness of the dwarf blue sheep. ZFY intron results showed an average of 0.51% sequence divergence, and one shared haplotype between the dwarf blue sheep and blue sheep. By analyzing an expanded data set that incorporated ZFY intron sequences of two additional Ovis (sheep) species-O. nivicola and O. ammon--we demonstrated that ZFY intron provides good resolution at the species and genus levels. The ZFY intron sequence divergence between dwarf blue sheep and blue sheep was comparable to that within the two Ovis species. Moreover, we found intraspecific sequence variation in ZFY intron for all three species examined. We propose that dwarf blue sheep be designated as a subspecies of blue sheep, P. n. schaeferi.

Animals↗
PubMedDate not supplied

Impaired conditioned taste aversion learning in spinophilin knockout mice.

Plasticity in dendritic spines may underlie learning and memory. Spinophilin, a protein enriched in dendritic spines, has the properties of a scaffolding protein and is believed to regulate actin cytoskeletal dynamics affecting dendritic spine morphology. It also binds protein phosphatase-1 (PP-1), an enzyme that regulates dendritic spine physiology. In this study, we tested the role of spinophilin in conditioned taste aversion learning (CTA) using transgenic spinophilin knockout mice. CTA is a form of associative learning in which an animal rejects a food that has been paired previously with a toxic effect (e.g., a sucrose solution paired with a malaise-inducing injection of lithium chloride). Acquisition and extinction of CTA was tested in spinophilin knockout and wild-type mice using taste solutions (sucrose or sodium chloride) or flavors (Kool-Aid) paired with moderate or high doses of LiCl (0.15 M, 20 or 40 mL/kg). When sucrose or NaCl solutions were paired with a moderate dose of LiCl, spinophilin knockout mice were unable to learn a CTA. At the higher dose, knockout mice acquired a CTA but extinguished more rapidly than wild-type mice. A more salient flavor stimulus (taste plus odor) revealed similar CTA learning at both doses of LiCl in both knockouts and wild types. Sensory processing in the knockouts appeared normal because knockout mice and wild-type mice expressed identical unconditioned taste preferences in two-bottle tests, and identical lying-on-belly responses to acute LiCl. We conclude that spinophilin is a candidate molecule required for normal CTA learning.

Animals↗
PubMedDate not supplied

The anti-tumor immune responses induced by a fusion protein of ovarian carcinoma anti-idiotypic antibody 6B11ScFv and murine GM-CSF in BALB/c mice.

Ovarian carcinoma anti-idiotypic antibody 6B11 was murine derived; we previously have cloned 6B11 single-chain Fv antibody (6B11ScFv) and constructed the 6B11ScFv/human granulocyte-macrophage colony stimulating factor (GM-CSF) fusion protein (designated as 6B11GM) to enhance the immunogenecity of the single-chain Ab(2). Because of the difference in species specificity between human GM-CSF and murine GM-CSF, there is no immune competent animal model on which the effect and metabolism of 6B11GM as a vaccine could be observed. In this study, 6B11mGM fusion gene was constructed by the fusing murine GM-CSF cDNA gene with 6B11ScFv. The fusion gene was cloned and expressed. The product of this gene is a fusion protein. It could specifically interact with the primary anti-ovarian carcinoma monoclonal antibody (COC166-9) and rat anti-mouse GM-CSF monoclonal antibody, respectively, and stimulate the growth of NFS-60 cells (a murine GM-CSF-dependent cell line). The specific anti-tumor immune response could be induced in BALB/c mice after immunized with anti-idiotypic fusion protein instead of ovarian carcinoma antigen without carrier proteins and adjuvant. Ab(3) could be detected in the sera of immunized mice with 6B11mGM by enzyme-linked immunoadsorbent assay test. Moreover, the fusion protein stimulated proliferation of CD4+ T cell from the spleen of BALB/c mice and proliferation of CD8+ T cell to a lesser degree. Therefore, 6B11mGM probably induces both humoral and cellular immunity against ovarian carcinoma in vivo.

Animals↗
PubMedDate not supplied

Characterization of differentially expressed genes in ovarian cancer by cDNA microarrays.

The molecular events leading to the development and progression of ovarian carcinoma are not completely understood. We performed a large-scale survey for the identification of differentially expressed genes between ovarian carcinoma and normal ovarian tissue by using cDNA microarray analysis. We utilized 512 member human novel putative oncogene and tumor suppressor gene cDNA microarrays to study the differences in gene expression between ovarian carcinoma and normal ovarian tissues. Some differentially expressed genes have been further confirmed by immunohistochemical analysis. A total of 39 differentially expressed genes were identified, of which 16 and 23 were specifically expressed in ovarian cancer and normal ovarian tissue, respectively. The comparison of average signal of differentially expressed genes exhibited at least a twofold difference in expression. The differentially expressed genes may be related to the carcinogenesis and progression of the malignant growth. The use of cDNA microarrays allows simultaneous monitor of the expression of many genes, thereby it speeds up the identification of differentially expressed genes. It is essential for further exploration of the mechanisms of the disease.

Adenocarcinoma↗
PubMedDate not supplied

Establishment and characterization of a human ovarian sarcomatoid carcinoma cell line BUPH:OVSC.

We first established a human ovarian sarcomatoid carcinoma cell line designated BUPH:OVSC from primary culture. The specimen was derived from the mural nodule in an ovarian mucinous tumor and cultured in vitro. To date, the cell line has been maintained for over 100 passages. Its biologic characteristics were studied by light and electron microscopy, which revealed spindle-shaped or polygonal cells with a doubling time of 39.5 h. The agglutination test of BUPH:OVSC was positive, and cell colonies were formed in soft agar. Chromosome analysis revealed its karyotype to be a pseudodiploidy. One X chromosome deletion and chromosome 20 addition were detected, and aberrant chromosomes t (1q;12q) and 14p(+) were its chromosome markers. BUPH:OVSC was tumorigenic in nude mice. Hematoxylin and eosin staining of transplanted tumors showed that the cells were morphologically sarcomatoid. However, the transmission electron microscopic observation exposed its epithelial origin. The cell line coexpresses cytokeratin and vimentin. It dose not appear to express estrogen and progesterone receptors or the CA125 tumor marker. Alcian blue/periodic acid-Schiff staining indicates that the cells could secrete acid mucopolysaccharide. In conclusion, BUPH:OVSC displays unique cellular properties, which make it a useful model for the study of human ovarian sarcomatoid carcinomas.

Agglutination Tests↗