Biomedical subjects

J Feng

Publications and source records attributed to J Feng.

At least 145 records · Page 8Linked to original sources

PubMed1999

Human breast carcinomal tissues display distinctive FTIR spectra: implication for the histological characterization of carcinomas.

Fourier transform infrared spectroscopic study of human breast normal and carcinomal tissues has been carried out. Some distinctive spectral differences which are mainly due to nucleic acids and proteins are observed between normal and carcinomal tissues. This method of analysis results in nearly 100% diagnostic accuracy of carcinomal tissues from normal tissues. The spectral patterns of well-differentiated carcinomal tissues exhibit marked heterogeneity, however that of poorly differentiated carcinomas demonstrate significant similarity. Apocrine, tubular, intraductal and mucinous carcinomas and invasive infiltrating ductal carcinomal tissues can be discriminated based on their characteristic spectra. The spectral differences confirm the possibility of using FTIR as an accurate and rapid technique to distinguish between normal and malignant breast tissues and classify breast carcinomas in different subtypes.

Adenocarcinoma↗

PubMed1999

Detection of virtually all mutations-SSCP (DOVAM-S): a rapid method for mutation scanning with virtually 100% sensitivity.

Dideoxy fingerprinting (ddF) was used as a tool to search for a generic set of conditions with sufficient power to detect virtually all mutations. For each condition tested, a very large sample of mutation-containing, single-stranded segments (about 1500) were analyzed with ddF. Correlation coefficients identified pairs of conditions in which single-strand conformation polymorphism (SSCP) mobilities were poorly correlated. The data strongly suggest that tertiary structure (e.g., base-sugar and sugar-sugar interactions) rather than secondary structure is the predominant determinant of mobility shifts by SSCP. Five conditions were selected with sufficient redundancy to detect all the mutations. The sensitivity of detection of virtually all mutations-SSCP (DOVAM-S) was determined by blinded analyses on samples containing additional mutations scattered throughout the eight exons and splice junctions in the factor IX gene. The factor IX gene sequence (2.5 kb) was scanned in one lane by 15 PCR-amplified segments (125 kb of sequence scanned per gel). All of the 84 single-base substitutions were detected in the blinded analyses, the first consisting of 50 hemizygous mutant and wild-type (WT) samples and the second consisting of 50 heterozygous mutant and WT samples. DOVAM-S is estimated to be five times faster than fluorescent DNA sequencing for the detection of virtually all mutations when the five conditions are applied.

Biotechnology↗

PubMed1999

[Detection of tumor cells in peripheral blood for patients with ovarian epithelial carcinoma].

OBJECTIVE: To detect tumor cell contamination of peripheral blood stem cell (PBSC) and the presence of tumor cells in peripheral circulating blood in patients with primary advanced ovarian cancer. METHODS: To establish limits of sensitivity of the immunocytochemical stainings technique (ABC method) for tumor cell detection, four types of ovarian cancer tumor cell(ovarian cancer cell lines SKOV3, 3AO, primary cancer cell from ascites of serous papillary carcinoma and undifferentiated adenocarcinoma) were added into normal blood to prepare the models with different ratios of tumor cells to mononuclear cells. Monoclonal antibodies(MAB) of COC 183 B2, CK(AE1/AE3) and their cocktail antibody (mixture of them) were used for immunocytochemical stainings. 14 blood specimens were examined (6 stem cell blood specimens, 8 primary advanced ovarian cancer blood spcimens). RESULTS: The sensitivity of detection achieved by cocktail antibodies was superior to either COC183B2 or CK MAb alone. The sensitivity of cocktail antibody was 1:5 x 10(5). According to the established sensitivity, none of the fourteen specimens contained tumor cell. CONCLUSIONS: None of the 6 PBSC specimens obtained from 2 patients and eight peripheral blood specimens obtained from 8 patients with primary ovarian epithelial carcinoma contained tumor cell.

Adenocarcinoma↗

PubMed1999

[In vitro study of 6B11GM to induce cellular immunity in patients with ovarian carcinoma].

OBJECTIVE: In order to explore the possibility of ovarian carcinoma anti-idiotypic single chain antibody (6B11scFV) and human granueocyte-macrophage colony stimulating factor (hGM-CSF) fusion protein 6B11GM as tumor vaccine. METHODS: Mononuclear cells, T cells and monocyte used as antigen presenting cell (APC) were separated from peripheral blood, and tumor cells were obtained from ascitic fluid in the same patients. In vitro T cell proliferation and autologous tumor cell cytotoxicity assay were applied. RESULTS: 6B11GM could induce T cell proliferation in vitro which was antigen specific. Cytotoxicity of mononuclear cells to autologous tumor cells increased after primed with 6B11GM. CONCLUSION: 6B11GM could induce efficient cellular immunity in patients with ovarian carcinoma, hopefully may be used for ovarian carcinoma vaccine.

Adenocarcinoma↗

PubMed1999

[Effects of nitric oxide on platelet function in burned rats].

OBJECTIVE: To investigate the effects of nitric oxide (NO) on rat platelet function after burn injury. METHODS: Wistar rats with 30% TBSA full thickness burns were used as model, indices of platelet functions including platelet aggregation rate in first minute (PAR-1), maximal platelet aggregation rate (PAR-m), platelet dissipation rate (PDR) and platelet adhesion rate (PAR) were determined in four groups, namely burn control (B), NO donor (sin-1), NO synthesis inhibitor (L-NAME) and the normal control (C). RESULTS: The PAR-1, PAR-m and PAR were significantly increased and the PDR was decreased remarkably after burn injury. In sin-1 group the PAR-1, PAR-m and PAR were obviously lower and the PDR was higher than that of B group (P < 0.05-0.01). In L-NAME group the PAR-1 was higher and the PDR was lower as compared with B group, but the PAR-m and PAR showed no significant differences between two groups. CONCLUSIONS: The ability of platelet adhesion and aggregation induced by activated platelet are increased after burn injury. NO can partially reduce the degree of platelet activation and inhibit platelet aggregation. Moreover, it may dissipate aggregated platelets.

Animals↗

PubMed1999

[Experimental study on the early liver injury and expression of TNF-alpha mRNA after burns complicated by endotoxemia].

OBJECTIVE: To observe the distribution and cell localization of TNF-alpha mRNA and its protein and study their role on pathogenesis of liver injury in rats. METHODS: An animal model in which rats were subjected to 20% TBSA III degree burns combined with intraperitoneal injection of lipopolysaccharide (LPS) was used for this experiment. The changes in the hepatic morphology, functions and TNF-alpha content in the serum and the expression, localization of liver TNF-alpha and TNF-alpha mRNA were determined with LM and EM, quantitative analysis, immunohistochemistry(IHC) and in situ hybridization (ISH). RESULTS: It was showed that there were sinusoid reaction, KCs activation and degeneration, necrosis of HCs, and platelets aggregation, fibrin deposition and PMNs attachment in sinusoid. The activity of ALT was obviously elevated and the content of ALB was slightly lowered. The contents of TNF-alpha in serum showed the peak values at 3 h. TNF-alpha was mainly localized in sinusoid endothelial cells(SECs), Kupffer cells (KCs) and TNF-alpha mRNA was mainly distributed in KCs, polymorphonuclear neutrophils (PMNs) and macrophages(MPs). CONCLUSION: The results suggest that the expression and localization of TNF-alpha mRNA and its protein are in agreement with the pathological changes of liver injury. TNF-alpha is one of the key cytokines in pathogenesis of liver injury in rats after burns complicated by endotoxemia.

Animals↗

PubMed1999

[Sex hormone receptor of hemangioma and vascular malformation in children].

OBJECTIVE: To investigate the level and difference of estrogen receptor (ER), progestogen receptor (PR) and androgen receptor (AR) in hemangioma tissues of Children. METHODS: 31 specimens of hemangioma and 36 specimens of vascular malformation were compound stained with hematoxylin-eosin and enzyme-linking affinitive immunohistochemistry. The prepared tissue slices were examined microscopically to find the ER, PR and AR in all the cells. RESULTS: The ER, PR and AR were detected in the two kinds of the tissue. However, their levels in the hemangioma were higher than those in the vascular malformation (P < 0.01) and the levels in the hemangioma of proliferating phase were higher than those in the hemangioma of regressive phase (P < 0.01). CONCLUSIONS: Hemangioma is one of the target tissues of estrogen. ER, PR and AR play an important role in the growth and development of hemangiomas. The binding site of the receptor may be occupied by extrogenous glucocorticoid so that hemangiomas gradually degenerates.

Adolescent↗

PubMed1999

[Intestinal blood perfusion improved by early enteral feeding in burned rat].

OBJECTIVE: To explore the mechanism of intestinal blood perfusion improved by early enteral feeding after burn injury. METHODS: Wistar rats were inflicted with 30% total body surface area full thickness flame burn and randomly divided into three groups: burned control (B), burned and early feeding (EF), and normal control (C). The content of endothelin (ET), nitric oxide (NO), vasoactive intestinal peptide (VIP), and intestine mucosal blood flow (IMBF) were determined at postburn 0, 3, 6, 12, 24, 48 hours. RESULTS: The content of ET, NO, VIP in small intestine as well as the ratio of ET/NO, ET/VIP were increased significantly and the IMBF was decreased markedly postburn. In EF group, ET, ET/NO and ET/VIP were significantly lower (P < 0.05, P < 0.01), and NO, VIP as well as IMBF were higher than those in B group (P < 0.05, P < 0.01). There were negative correlation between ET/NO, ET/VIP and IMBF (r(1) = -0.95, P < 0.01; r(2) = -0.87, P < 0.01). CONCLUSIONS: The mechanism of intestinal blood perfusion improved by early enteral feeding may be correlated with increased NO, VIP and decreased ET induced by foods stimulating intestinal nerve.

Animals↗

PubMed1999

[Clinical study of various growth factors on the improvement of impaired healing ulcers in patients with diabetic disease].

OBJECTIVE: To investigate clinical effects and possible mechanisms of various growth factors on impaired healing ulcers of patients with diabetic disease. METHODS: Seventy-eight patients were divided into three groups; saline control, epidermal growth factor(EGF) experimental group, and platelet-derived wound healing factor (PDWHF) experimental group. General healing conditions, wound closing index, healing rates and histological changes of the patient's ulcer wound were observed during 1-8 weeks after treatment. RESULTS: The wound closing index and healing rate of ulcers were significantly increased in the EGF and PDWHF experimental groups compared with the control group, while the angiogenesis, fibroblast hyperplasia, and collagen deposit were more obvious in EGF and PDWHF experimental groups than that of control group. The promoting effects on wound healing in PDWHF experimental group were better than in EGF group. CONCLUSION: It suggests that local application of certain growth factor alone or various growth factors together is an effective method to improve the condition of impaired healing of diabetic ulcers.

Aged↗

PubMed1999

[Free radicals on cataracts induced by sodium selenite studied by ESR and LPO].

We made a electron spin resonance (ESR) study on rat cataracts induced by Na2SeO3. A signal was detected at about g = 2.0026, and the content of electron spins (CES) in lens of rat administrated Na2SeO3 for a short time is higher than that of control significantly. At the late stage of cataracts, the content of CES was lower than normal level. The results of kinetics analysis showed that the CES grow up with the administration of Na2SeO3 and decays in index-law after administration. The results suggested that free radical scavengers or antioxidants should be useful for preventing cataracts at initial stage of the oxidation damage to lens, but they could aggravate cataracts at late stage of cataracts. This can explain the controversy about the curative effect of antioxidant to cataracts.

Animals↗

PubMed1999

[A novel chiral selector in capillary electrophoresis--beta-cyclodextrin polymer].

Three chiral selectors CM-beta-CD, EP-beta-CD, beta-CD were studied for the enatio-separation of three drugs under optimum conditions respectively. The results demonstrate that the resolving power for the drugs is as follows CM-beta-CD > EP-beta-CD > beta-CD, with the exception of lobeline. This is due to the--CH2COOCH3 group of CM-beta-CD, which will change the combination and improve the recognition on guest molecules. Although EP-beta-CD is inferior to CM-beta-CD for the separation of chlorpheniramine and verapamil, it has excellent recognition on lobeline and it has not been reported previously. In most cases EP-beta-CD is superior to beta-CD. The explanations are: (1) EP-beta-CD has good solubility in water, which enables high concentrations to be used and consequently achieves excellant separation of racemic compounds, (2) the polymerization of beta-CD changes the properties of CD units and the process produces a more rigid and different conformation from CD, (3) we must attribute much merits to the cooperation or synergism of two, three or even more CD moieties of two polymers for inclusion. Complexation with analytes possesses more than one guest part in their structure.

Anti-Allergic Agents↗

PubMed1998

Signaling by the cytokine receptor superfamily.

A variety of cytokines that regulate functions of multiple lineages share the utilization of receptors that are structurally and functionally related and are referred to as the cytokine receptor superfamily. These receptors associate with one or more of the four mammalian Janus kinases (Jaks) and ligand-induced receptor aggregation results in their activation. Critical roles for Jak3 and Jak2 are demonstrated by the phenotypes of mice that lack each gene. Among the substrates of the Jaks are one or more of the seven members of the signal transducers and activators of transcription (Stats). Each Stat family member plays a critical role in the biological functions of specific cytokines as demonstrated by the phenotype of mice lacking one or more of these genes.

Animals↗

PubMed1998

Interaction of myosin phosphatase target subunit 1 with the catalytic subunit of type 1 protein phosphatase.

In the investigation of the sequences of myosin phosphatase target subunit 1 (MYPT1) involved in binding the substrate and catalytic subunit of protein phosphatase type 1 (PP1c), fragments of MYPT1 were prepared and characterized. The shortest fragment capable of full activation of PP1c contained the sequence of residues 1-295. Within this fragment, the N-terminal sequence of residues 1-38 is involved in activation of PP1c (kcat) and the ankyrin repeats (residues 39-295) were involved in substrate binding (Km). The ankyrin repeats alone (residues 39-295) and the C-terminal fragment of residues 667-1004 did not activate PP1c. Using gel filtration, an interaction with PP1c was detected for the sequences of residues 1-295, 17-295, and 1-170. Affinity columns were prepared with various fragments to assess binding of PP1c. Binding to the column with residues 1-295 was strongest, followed by the binding to the column with residues 1-170. A weak interaction was observed with the column with residues 1-38. The column with residues 1-295 was used to isolate PP1c from gizzard. The purified PP1c was activated by MYPT1 and fragments to a greater extent than previous preparations. These results suggest that the N-terminal sequence (residues 1-38) and the ankyrin repeats are involved in binding PP1c. The C-terminal ankyrin repeats appear to be dominant, but there is an interaction of PP1c with the N-terminal ankyrin repeats. The N-terminal peptide has two apparent functions, the binding of PP1c via the consensus binding sequence and activation of PP1c by the sequence of residues 1-16.

Animals↗

PubMed1998

Replication of R6K gamma origin in vitro: discrete start sites for DNA synthesis dependent on pi and its copy-up variants.

The regulation of the plasmid R6K gamma origin (gamma ori) is accomplished through the ability of the pi protein to act as an initiator and inhibitor of replication. Hyperactive variants of this protein, called copy-up pi, allow four to tenfold increases of gamma ori plasmid DNA in vivo. The higher activity of copy-up pi variants could be explained by an increase in the initiator function, a decrease in the inhibitor activity, or a derepression of a more efficient mechanism of replication that can be used by wt pi (pi35. 0) only under certain conditions. We have compared the replication activities of wt pi35.0 and copy-up pi mutants in vitro, and analyzed the replication products. It is shown that copy-up variants are several-fold more active than wt pi35.0 in replication. This appears to be due to enhanced specific replication activity of copy-up mutants rather than elevated fractions of protein proficient in DNA binding. Furthermore, biochemical complementation revealed that pi200 (copy-up) is dominant over wt pi35.0. The elevated activity of copy-up pi is not caused by an increased rate of replisome assembly as inferred from in vitro replication assays in which the lag periods observed were similar to that of wt pi35.0. Moreover, only one round of semiconservative, unidirectional replication occurred in all the samples analyzed indicating that copy-up pi proteins do not initiate multiple rounds of DNA synthesis. Rather, a larger fraction of DNA template replicates in the presence of copy-up pi as determined by electron microscopy. Two clusters of discrete DNA synthesis start sites are mapped by primer extension near the stability (stb) locus of the gamma ori. We show that the start sites are the same in the presence of wt pi35.0 or copy-up proteins. This comparative analysis suggests that wt pi35.0 and copy-up variants utilize fundamentally similar mechanism(s) of replication priming.

Amino Acid Substitution↗

PubMed1998

Variants in the alpha2A AR adrenergic receptor gene in psychiatric patients.

In various studies of psychiatric patients, alterations in adrenergic receptor (AR) expression or function have been suggested. Herein, the alpha2A AR gene was screened in 206 patients with schizophrenia, attention deficit hyperactivity disorder (ADHD), autism, alcohol dependence, or cocaine dependence. The entire coding region was examined for single base pair changes, using restriction endonuclease fingerprinting (REF), a screening method that can detect virtually 100% of mutations in 2-kb DNA segments. In the approximately 600 kb of screened sequence, six novel nucleotide changes were identified. The changes resulted in four missense changes (A25G, N251K, R368L, and K370N), and a sequence in the 3' untranslated region. In addition, a silent change (G363G) was found at high frequency in Asians and Native Americans. Of the four missense changes, two found in patients with alcohol/drug dependence occur in highly conserved amino acids, suggesting that these are of likely functional significance. As the alpha2A ARs are widely distributed both pre- and postsynaptically, and as many pharmacological agents with multiple effects target these receptors, the novel missense changes described herein may be candidates for involvement in alcohol/drug dependence, in other clinical disorders or traits, or in differential response to pharmacotherapy.

Animals↗

PubMed1998

Ionic mechanisms of regional action potential heterogeneity in the canine right atrium.

Atrial action potential heterogeneity is a major determinant of atrial reentrant arrhythmias, but the underlying ionic mechanisms are poorly understood. To evaluate the basis of spatial heterogeneity in canine right atrial repolarization, we isolated cells from 4 regions: the crista terminalis (CT), appendage (APG), atrioventricular ring (AVR) area, and pectinate muscles. Systematic action potential (AP) differences were noted: CT cells had a "spike-and-dome" morphology and the longest AP duration (APD; value to 95% repolarization at 1 Hz, 270+/-10 ms [mean+/-SEM]); APG and pectinate muscle cells had intermediate APDs (180+/-3 and 190+/-3 ms, respectively; P<0.001 versus CT for each), with APG cells having a small phase 1; and AVR cells had the shortest APD (160+/-4 ms, P<0.001 versus other regions). The inward rectifier and the slow and ultrarapid delayed rectifier currents were similar in all regions. The transient outward K+ current was significantly smaller in APG cells, explaining their small phase 1 and high plateau. L-type Ca2+ current was greatest in CT cells and least in AVR cells, contributing to their longer and shorter APD, respectively. The E-4031-sensitive rapid delayed rectifier K+ current was larger in AVR cells compared with other regions. Voltage- and time-dependent current properties were constant across regions. We conclude that myocytes from different right atrial regions of the dog show systematic variations in AP properties and ionic currents and that the spatial variation in ionic current density may explain AP differences. Regional variation in atrial ionic currents may play an important role in atrial arrhythmia generation and may present opportunities for improving antiarrhythmic drug therapy.

Action Potentials↗

PubMed1998

Akt activation by growth factors is a multiple-step process: the role of the PH domain.

The protein kinase encoded by the Akt proto-oncogene is activated by phospholipid binding, membrane translocation and phosphorylation. To address the relative roles of these mechanisms of Akt activation, we have employed a combination of genetic and pharmacological approaches. Transient transfection of NIH3T3 cells with wild-type Akt, pleckstrin homology (PH) domain mutants, generated on the basis of a PH domain structural model, and phosphorylation site Akt mutants provided evidence for a model of Akt activation consisting of three sequential steps: (1) a PH domain-dependent, growth factor-independent step, marked by constitutive phosphorylation of threonine 450 (T450) and perhaps serine 124 (S124), that renders the protein responsive to subsequent activation events; (2) a growth factor-induced, PI3-K-dependent membrane-translocation step; and (3) a PI3-K-dependent step, characterized by phosphorylation at T308 and S473, that occurs in the cell membrane and is required for activation. When forced to translocate to the membrane, wild-type Akt and PH domain Akt mutants that are defective in the first step become constitutively active, suggesting that the purpose of this step is to prepare the protein for membrane translocation. Both growth factor stimulation and forced membrane translocation, however, failed to activate a T308A mutant. This, combined with the finding that T308D/S473D double mutant is constitutively active, suggests that the purpose of the three-step process of Akt activation is the phosphorylation of the protein at T308 and S473. The proposed model provides a framework for a comprehensive understanding of the temporal and spatial requirements for Akt activation by growth factors.

3T3 Cells↗

PubMed1998

Direct fractionation of proteins in particle-containing feedstocks by a filter paper pieces-based DEAE-cellulose column chromatography. Rapid, robust and low-cost capturing procedure for protein.

Filter paper pieces-based (FPB) DEAE-celluloses was prepared for direct fractionation of proteins in particle-containing feedstocks. FPB DEAE-cellulose has a protein binding capacity equivalent to that of commercially available DEAE-cellulose. Crude extracts from porcine intestine and kiwi fruit pulp, which were unmanageable by commercially available chromatographic media due to rapid clothing, could be directly fractionated with FPB DEAE-cellulose column. In addition, effluents from an FPB DEAE-cellulose column were extensively clarified. The present approach can be used as a rapid, robust and low-cost capturing step for protein from particle-containing feedstocks.

Animals↗