PubMed Health⌕ Search

Biomedical subjects

J Deng

Publications and source records attributed to J Deng.

At least 109 records · Page 6Linked to original sources
PubMed1998

Lamina-specific cell adhesion on living slices of hippocampus.

Laminar distribution of fiber systems is a characteristic feature of hippocampal organization. Ingrowing afferents, e.g. the fibers from the entorhinal cortex, terminate in specific layers, which implies the existence of laminar recognition cues. To identify cues that are involved in the laminar segregation of fiber systems in the hippocampus, we used an in vitro assay to study the adhesion of dissociated entorhinal cells on living hippocampal slices. Here we demonstrate that dissociated entorhinal cells adhere to living hippocampal slices with a lamina-specific distribution that reflects the innervation pattern of the entorhino-hippocampal projection. In contrast, laminae which are not invaded by entorhinal fibers are a poor substrate for cell adhesion. Lamina-specific cell adhesion does not require the neural cell adhesion molecule or the extracellular matrix glycoprotein reelin, as revealed in studies with mutants. However, the pattern of adhesive cues in the reeler mouse hippocampus mimics characteristic alterations of the entorhinal projection in this mutant, suggesting a role of layer-specific adhesive cues in the pathfinding of entorhinal fibers. Lamina-specific cell adhesion is independent of divalent cations, is abolished after cryofixation or paraformaldehyde fixation and is recognized across species. By using a novel membrane adhesion assay, we show that lamina-specific cell adhesion can be mimicked by membrane-coated fluorescent microspheres. Recognition of the adhesive properties of different hippocampal laminae by growing axons, as either a growth permissive or a non-permissive substrate, may provide a developmental mechanism underlying the segregation of lamina-specific fiber projections.

Afferent Pathways↗
PubMed1998

[A prospective study on accidental deaths among 0-14-year-old children in Jiangsu, 1994-1995].

By stratified cluster random sampling, a prospective study on the accidental deaths of 0-14 years old children during 1994-1995 wsa carried on in a population size of 2.29 millions in four citys and nine counties in Jiangsu province. Results showed that the average mortality of accidents was 53.0 per 10(5) among children aged 0 to 14 and accidental death was the leading cause of deaths taking up 37.6% among the deaths of the 0-14 years old. Accidental deaths ranked fourth, took up 15.3% in infancy deaths making up about 70% in their deaths, and ranked first in the age groups 1-4 and 5-14. The three leading causes of accidental deaths in the urban and rural area were drowning, accidental suffocation and motor vehicle injuries. Accidental suffocation was the number one cause of accidental death in infants, making up 85% of the total accidental deaths. Drowning was the leading cause of accidental deaths in 1-4 and 5-14-year-old children, making up 70% and 50% of accidental deaths respectively. Motor vehicle injuries took the lead among accidental deaths in the cities.

Accidents↗
PubMed1998

Production of longer acting tissue plasminogen activator of humans in milk of transgenic mice.

An exogenous gene was expressed in the mammary epithelium of transgenic mice in the hope that the encoded protein could be secreted into milk. The transgenic mice carrying the promoter and upstream regulatory sequences from the sheep BLG gene which were fused to cDNA encoding human tissue plasminogen activator (tPA) with its endogenous secretion signal sequence were generated. The hybrid genes were microinjected into mouse embryos. Two mice were identified as being transgenic by Southern blot. Milk obtained from lactating females contained biologically active tPA, and its concentration was calculated to be about 1.5 microg/ml. This result establishes the feasibility of secreting protein into the milk of transgenic animals for production of biologically active tPA proteins, and may provide a powerful method to produce such proteins on a large scale.

Animals↗
PubMed1998

Detection of gsp oncogene in growth hormone-secreting pituitary adenomas and the study of clinical characteristics of acromegalic patients with gsp-positive pituitary tumors.

OBJECTIVE: To investigate the incidence and clinical characteristics of gsp oncogene positive growth hormone-secreting adenomas of Chinese acromegalic patients. METHODS: Continuously 40 patients were studied. Serum hormone levels of pituitary and target glands were measured and growth hormone (GH)-TRH stimulating tests were done before transsphenoidal or transfrontal hypophysectomy. Deoxyribonucleic acid (DNA) was extracted from the frozen tumor tissue, and the DNA fragment encompassing codon 201 and 227 of the Gs alpha gene was amplified by polymerase chain reaction (PCR). Point mutations at codon 201 and 227 were detected using PCR direct sequencing method in order to get the incidence of gsp oncogene in GH secreting adenomas. RESULTS: Of 40 tumors studied, 22 (55%) were gsp positive. The point mutation from CGT (Arg) to TGT (Cys) at codon 201 was detected in 21 pituitary tumors, but the point mutation from CAG (Gln) to CTG (Leu) at codon 227 of the Gs alpha gene was found in only 1 tumor. All of the point mutations are heterozygous. The number of gsp positive patients which have 30% or more decrease of serum GH concentration after glucose inhibition is less than that of gsp negative patients (P = 0.042). Compared to gsp negative patients, most of gsp positive patients showed paradoxical response to TRH stimulation (P = 0.002). There were more gsp positive patients with the tumor diameter less than 25 mm (P = 0.029) and with normal GH levels in OGTT after surgery (P = 0.007). CONCLUSIONS: Gsp mutation is one of the major intrinsic defects in the pathogenesis of growth hormone-secreting pituitary tumors and the identification of gsp mutation can be a reference for classification and prognosis of GH tumors.

Acromegaly↗
PubMed1998

[Separation of alkaloids in tea by high-speed counter-current chromatography].

Alkaloids extracted from the green tea were separated by high-speed counter-current chromatography. A series of experiments have been performed to investigate effects of different solvent system. A system of CHCl3-CH3OH-NaH2PO4(23 mmol/L) = (4:3:2) was selected, in which the upper phase was used as the stationary phase, and the lower phase as mobile phase. When acidity of solvent system is pH 5.6, three chemical components are very efficiently isolated by one injection of 50 mg sample mixture. Analyzing the eluted fractions by TLC, we know that one is caffeine, and the other is theophylline. In comparing the separation results by high-speed counter-current chromatography with those by TLC, the advantages of this method is verified. It should find wide applications of this technology for the separation of crude mixture of plant components.

Alkaloids↗
PubMed1998

[Effects of isorhapotigenin and resveratrol on function of peripheral blood polymorphonuclear leukocytes from rabbits].

In effects of isorhapotigenin and resveratrol on chemotaxis and release of beta-glucuronidase from rabbit peripheral blood polymorphonuclear leukocytes stimulated with formylmethionyl-leucyl-phenyl-phenylalanine (fMLPP) were studied. The optimal concentration of fMLPP for the induction of chemotaxis of polymorphonuclear leukocytes was approximately at 5 x 10(-10) mol.L-1. fMLPP, at the concentration range of 10(-10)-10(-6) mol.L-1, dose-dependently increased the release of beta-glucuronidase from polymorphonuclear leukocytes. Isorhapotigenin and resveratrol both inhibited the chemotaxis of polymorphonuclear leukocytes stimulated with fMLPP(5 x 10(-10) mol.L-1). Isorhapotigenin, at the concentration range of 10(-5)-10(-4) mol.L-1, dose-dependently inhibited the release of beta-glucuronidase from polymorphonuclear leukocytes stimulated with fMLPP(10(-8) mol.L-1). Resveratrol, at the concentrations of 1 x 10(-5) and 3 x 10(-5) mol.L-1, was shown to dose-dependently inhibit beta-glucuronidase release from polymorphonuclear leukocytes stimulated with fMLPP(10(-8) mol.L-1).

Animals↗
PubMed1998

[Isolation, detection toxicity and structure of toxin from Beauveria bassiana].

In this experiment, the crude toxin from the metabolite of Beauveria bassiana was isolated and its toxicity was detected. The result shows that indicates toxin has toxicity on larva of Aedesalbopictus obvious. Though it with low toxicity to larva of Heliothis zea when swallowed, but has high toxicity when injected into the blood. For bacteria it only inhibites G+. When it applied to cultured cells of Spodoptera frugiperda sf-21, the regression equation of toxicity is y = 2.03 + 2.39x. The half lethal concentration (LC50) is 0.01751%. 95% believable limit is 0.01517-0.0202%. There are three substances which have similar atomic group when analysed by HPLC and infrared spectrum.

Aedes↗
PubMed1998

Rieger syndrome.

PURPOSE: To discuss the clinic features of Rieger syndrome, the reasons of making wrong diagnosis, the way of treatment, and the research progress of its molecular characterization and gene mapping of this syndrome. METHODS: Two cases of Rieger syndrome which affected a patient and his daughter were studied. Multiple clinical examinations including photography of anterior segment, gonioscopy and fundus, Humphrey perimetry, A-scan ultrasonography, multiple tonometry in a day and chromosome examination were performed. Most importantly, ultrasonic biomicroscope (UBM) was first used to show the abnormalities of anterior segment in this syndrome. RESULTS: Gonioscopic examination revealed many mesoderm tissues remained and some parts of the iris adhered to cornea. In addition to cornea, iris and chamber angle, UBM showed that there was also hypoplasia of ciliary body. The result of the chromosome examination indicated normal. CONCLUSIONS: Rieger syndrome is an autosomal-dominated disorder with mesoderm dysgenesis. Recent researches have confirmed that a locus for this syndrome maps to 4q25. Besides hypoplasia of cornea, iris and chamber angle, its ocular phenotype maybe include dysgenesis of ciliary body which is probably one of the reasons of secondary glaucoma.

Abnormalities, Multiple↗
PubMed1997

Inhibition of nuclear factor-kappaB activity is involved in E1A-mediated sensitization of radiation-induced apoptosis.

The adenoviral E1A protein has been implicated in the potentiation of apoptosis induced by various external stimuli, but the exact mechanism of that potentiation is not clear. In this study, we compared the sensitivity to ionizing gamma-irradiation of E1A transfectants with that of parental cells in a human ovarian cancer cell line (SKOV3.ip1); we found that the E1A transfectants became sensitive to radiation-induced apoptosis. Recently, activation of the transcription factor nuclear factor-kappaB (NF-kappaB) has been shown to play a key role in the anti-apoptotic pathway of radiation-induced apoptosis. In an attempt to determine whether NF-kappaB was involved in the E1A-mediated sensitization of radiation-induced apoptosis, we found that radiation-induced activation of NF-kappaB occurred in the parental cells but was blocked in the E1A transfectants. Furthermore, parental cells cotransfected with NF-kappaB and E1A were better protected from undergoing apoptosis upon irradiation than those transfected with E1A alone. Thus, our results suggest that inhibition of NF-kappaB activation by E1A is a plausible mechanism for E1A-mediated sensitization of radiation-induced apoptosis.

Adenovirus E1A Proteins↗
PubMed1997

Adenovirus-mediated overexpression of the transcription factor E2F-1 induces apoptosis in human breast and ovarian carcinoma cell lines and does not require p53.

Apoptosis is a mode of cell death that is carefully regulated based on cellular and environmental signals. The ability to modulate the individual cellular machinery and thereby to promote apoptosis is an important strategy in cancer therapy. It has previously been shown that overexpression of the transcription factor E2F-1 can induce apoptosis in quiescent rat embryo fibroblasts. This effect has been reported to occur in a p53-dependent manner. To investigate whether overexpression of E2F-1 could also induce apoptosis in human cancer cells, a recombinant adenovirus vector containing the transgene E2F-1 under control of the cytomegalovirus promoter (Ad5CMVE2F) was used to induce high levels of the E2F-1 protein in human breast and ovarian carcinoma cell lines. Significant morphological changes occurred in four of the five cell lines within 48 h of transduction with the Ad5CMVE2F. These changes were consistent with apoptosis, which was confirmed further by DNA fragmentation assay and fluorescence-activated cell sorting analysis. On the basis of these assays, which show that apoptosis occurred in those cell lines with mutations in the p53 gene, we suggest that the induction of E2F-1-mediated apoptosis does not require wild-type p53 when E2F-1 is overexpressed using an adenovirus-based strategy.

Adenoviridae↗
PubMed1997

Characterization of immobilization of an enzyme in a modified Y zeolite matrix and its application to an amperometric glucose biosensor.

A new approach to construct an amperometric biosensor is described. Without using bovine serum albumin-glutaraldehyde, glucose oxidase (GOx) was immobilized on a dealuminized Y zeolite (DAY)-modified platinum electrode to construct a glucose sensor. The large specific surface area of the zeolite substrate resulted in high enzyme loading. The immobilized GOx in this manner was stable and could maintain its high activity for at least 3 months. The interactions between the zeolite and the enzyme were investigated by means of Fourier transform infrared spectra, and the pore distribution and the surface acid property of DAY were preliminarily studied. The results showed that the hydrophilic property and the existing mesopores of DAY played important roles in the enzyme immobilization. This resulting biosensor exhibited good reproducibility and selectivity, owing to the uniform pore structure and unique ion-exchange property of the zeolite. The biosensor responded rapidly to glucose in the linear range from 2.0 x 10(-6) to 3.0 x 10(-3) M, with a detection limit of 0.5 microM.

Biosensing Techniques↗
PubMed1997

Interactions between protein kinase C and pleckstrin homology domains. Inhibition by phosphatidylinositol 4,5-bisphosphate and phorbol 12-myristate 13-acetate.

Pleckstrin homology (PH) domains comprised of loosely conserved sequences of approximately 100 amino acid residues are a functional protein motif found in many signal-transducing and cytoskeletal proteins. We recently demonstrated that the PH domains of Tec family protein-tyrosine kinases Btk and Emt (equal to Itk and Tsk) interact with protein kinase C (PKC) and that PKC down-regulates Btk by phosphorylation. In this study we have characterized the PKC-BtkPH domain interaction in detail. Using pure PKC preparations, it was shown that the Btk PH domain interacts with PKC with high affinity (KD = 39 nM). Unlike other tested phospholipids, phosphatidylinositol 4,5-bisphosphate, which binds to several PH domains, competed with PKC for binding to the PH domain apparently because their binding sites on the amino-terminal portion of the PH domains overlap. The minimal PKC-binding sequence within the Btk PH domain was found to correspond roughly to the second and third beta-sheets of the PH domains of known tertiary structures. On the other hand, the C1 regulatory region of PKCepsilon containing the pseudosubstrate and zinc finger-like sequences was found to be sufficient for strong binding to the Btk PH domain. Phorbol 12-myristate 13-acetate (PMA), a potent activator of PKC that interacts with the C1 region of PKC, inhibited the PKC-PH domain interaction, whereas the bioinactive PMA (4-alpha-PMA) was ineffective. The zeta isoform of PKC, which has a single zinc finger-like motif instead of the two tandem zinc finger-like sequences present in conventional and novel PKC isoforms, does not bind PMA. Thus, as expected, PH domain binding with PKCzeta was not interfered with by PMA. Further, inhibitors that are known to attack the catalytic domains of serine/threonine kinases did not affect this PKC-PH domain interaction. In contrast, the presence of physiological concentrations of Ca2+ induced less than a 2-fold increase in PKC-PH domain binding. These results indicate that PKC binding to PH domains involve the beta2-beta3 region of the Btk PH domain and the C1 region of PKC, and agents that interact with either of these regions (i.e. phosphatidylinositol 4,5-bisphosphate binding to the PH domain and PMA binding to the C1 region of PKC) might act to regulate PKC-PH domain binding.

Amino Acid Sequence↗
PubMed1997

Construction and overexpression of a synthetic gene for human DNA methylguanine methyltransferase: renaturation and rapid purification of the protein.

A synthetic gene was constructed that encodes human DNA methylguanine methyltransferase (hMGMT). The synthetic gene was designed with a number of unique restriction sites to facilitate cassette mutagenesis and to reflect the preferences found among genes in Escherichia coli. Both the full-length gene and a gene for a functional variant (hMGMT delta C) that lacks the C-terminal 28 codons were constructed, and the genes were overexpressed using a T7 RNA polymerase promoter. The proteins are made in the form of insoluble aggregates but the truncated form of the protein (hMGMT delta C) has been successfully denatured, renatured, and purified to near homogeneity by ion exchange. Methyltransferase activity assays of hMGMT delta C demonstrate that the reconstituted protein has substantial DNA repair activity, though somewhat less than full-length hMGMT that had been expressed and purified in a soluble form. Mass spectrometry of a mixture of proteolytic fragments confirmed the protein sequence and indicated no detectable oxidation of the active site cysteine. The protein was determined to be monomeric by gel filtration chromatography, and circular dichroism spectra for renatured hMGMT delta C and fully soluble hMGMT are consistent with the renatured protein preparation being fully folded. Refolded hMGMT delta C had a curious propensity to form large aggregates in a time-dependent manner when injected into a dynamic light scattering instrument; this aggregation behavior was not observed for hMGMT purified in a soluble form. Differences in susceptibility to aggregation may account for differences in methyltransfer activity. Yields of purified protein were approximately 5 mg/liter of culture.

Amino Acid Sequence↗
PubMed1997

Amphotericin B enzyme-linked immunoassay for clinical use: comparison with bioassay and HPLC.

OBJECTIVE: To evaluate a new enzyme-linked immunosorbent assay (ELISA) for amphotericin B in serum samples. Results are compared with those obtained by HPLC and bioassay. DESIGN: Comparison of results obtained by ELISA, HPLC, and bioassay. METHODS: We developed a new ELISA using a polyclonal rabbit antibody to measure serum amphotericin B concentrations. Blinded samples of amphotericin B in concentrations of 0.15-78 micrograms/mL were prepared in human serum and assayed simultaneously by the ELISA, HPLC, and bioassay. The results of each assay were derived from standard curves and evaluated by using the Table Curve 2D computer program. These data were compared by using correlation analysis with evaluation of Pearson's correlation coefficient by Student's t-test. RESULTS: ELISA and bioassay compared favorably at amphotericin B concentrations of 0.3-20 micrograms/mL with a correlation coefficient of r = 0.993, while ELISA and HPLC compared with a correlation coefficient of r = 0.944. The average coefficient of variation over the range 0.3-20.0 micrograms/mL was 28% +/- 7% for HPLC, 26% +/- 9% for ELISA, and 13% +/- 4% for bioassay. Comparison of all three assays revealed the highest correlation with the ELISA assay (r = 0.998) for the range of concentrations (0.3-20 micrograms/mL) routinely achieved. Samples containing concentrations in excess of 20 micrograms/mL could be diluted. Desiccation for concentrations less than 0.3 microgram/mL was not tested. CONCLUSION: The determination of serum amphotericin B concentrations by ELISA gave results similar to those obtained by a bioassay and HPLC technique. Although variability appears greater with ELISA, the ease of performing yjis assay expedites the evaluation of amphotericin B concentrations from lipid formulations without interference from coadministered antibacterials of azole antifungals.

Amphotericin B↗
PubMed1997

Investigation of plasma membrane-associated apolipoprotein E in primary macrophages.

Our previous studies identified the lysosome as the compartment for degradation of newly synthesized apoE in primary macrophages. Lysosomal degradation of newly synthesized apoE is extensive and rapid (> 50% in 60 min). In the present study we tested the hypothesis that the macrophage cell surface is part of the itinerary of apoE in its path to the lysosomes. We therefore examined the existence and size of the apoE pool associated with the macrophage cell surface. Such a pool may not only provide a mechanism of targeting apoE for lysosomal degradation, by endocytosis, but also have important implications for the metabolism of lipoproteins by macrophages. Treatment of macrophages with heparin (10 micrograms/ml and 5 mg/ml) and heparinase I (1 U/ml), which releases substantial amounts of apoE from HepG2 cells, results in no additional release of apoE from macrophages. Treatment of macrophages with xyloside (1 mM) or GRGDTP (500 micrograms/ml) does not decrease the extent of cell-associated apoE. Both immunogold labeling, followed by electron microscopy, and immunofluorescent labeling and light microscopy further confirm the lack of significant amounts of cell surface-associated apoE in macrophages. In contrast, immunolabeled apoE is readily observed in permeabilized cells. Taken together, these data indicate the absence of significant apoE-glycosaminoglycan interaction at the macrophage cell surface. The lack of such an interaction is likely due to paucity of heparan sulfate proteoglycans on the macrophage cell surface, when compared to hepatocytes. Along with our previous observations. (Deng. J., V. Rudick, and L. Dory, 1995. J. Lipid Res. 36:2129-2140), these results suggest direct targeting of a portion of newly synthesized apoE from trans-Golgi network to lysosomes for degradation, without involving the plasma membrane and endocytosis.

Animals↗
PubMed1997

Immunoreactive growth hormone in human peripheral T lymphocytes: encoding sequence of cDNA identical to that of the pituitary human growth hormone.

OBJECTIVE: To detect the cDNA sequence of immunoreactive growth hormone (irGH) in human lymphocytes and to compare it with that of human growth hormone (hGH) in the pituitary. METHODS: The mRNA of irGH in human peripheral blood mononuclear cells (PBMC) was detected by Northern blot analysis. The cDNA of irGH was obtained by reverse-transcriptase and polymerase chain reaction amplification and obtained by screening from a cDNA library of human T lymphocytes. The sequence of irGH cDNA was determined and compared with that of the pituitary hGH. RESULTS: Very low level of irGH mRNA was detected in human PBMCs by Northern blot analysis. The cDNA sequence of the entire open reading frame of human irGH was 651 bp, which is identical to that of pituitary hGH. CONCLUSIONS: The same hGH molecule can be produced by human pituitary somatotrophic cells and human peripheral lymphocytes.

Amino Acid Sequence↗