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Biomedical subjects

X Dong

Publications and source records attributed to X Dong.

At least 199 records · Page 11Linked to original sources
PubMed1994

Expression of intestinal fatty acid binding protein in intestinal epithelial cell lines, hBRIE 380 cells.

Intestinal fatty acid binding protein (I-FABP) is a cytosolic protein present only in differentiated intestinal epithelial cells. Here we report on an intestinal cell culture system expressing I-FABP during cell differentiation and the modulation of expression by extracellular factors. An I-FABP-expressing cell line (hBRIE 380i) was generated from Berkeley rat intestinal epithelial cells (hBRIE 380). Time- and substratum-dependent changes in I-FABP mRNA expression were paralleled by changes in protein levels. Induction of I-FABP levels observed on collagen type I gels in the presence of limiting serum was prevented by insulin. When cells were grown on collagen gels containing fibronectin and laminin, a stimulation of ultrastructural characteristics of cell differentiation was observed with no further induction of I-FABP expression. The data show that I-FABP expression is limited to a differentiated population of hBRIE 380i cells and that the expression can be regulated by factors present in the extracellular matrix as well as involved in regulation of replication or metabolic state of the cell.

Animals↗
PubMed1994

[Effects of electrical stimulation of S II and electroacupuncture on contents of some free amino acids in the precruciate cortex].

Effects of electrical stimulation of the somatosensory area II (S II) of the cerebral cortex and electroacupuncture (EA) on contents of r-aminobutyric acid (GABA), glutamic acid (Glu), aspartic acid (Asp) and alanine (Ala) in the precruciate cortex (PreCtx) were investigated in order to probe if the free amino acids in the preCtx are involved in the S II descending modulation and acupuncture analgesia. Adult cats were randomly divided into four groups: control, EA, electrical stimulation of S II and stimulation of S II plus EA. EA was applied at right Huantiao and Yanglingquan acupoints for 30 min and electrical stimulation was given on the S II surface. Amino acids were separated by paper chromatography and determined with spectrophotometry. Results showed that the stimulation of S II or/and EA had no significant effects on the contents of GABA, Glu, Asp and Ala in the PreCtx, indicating that the four amino acids are probably not involved in regulatory effects of EA and the stimulation of S II on the PreCtx.

Animals↗
PubMed1994

[An experimental study on cultivation of human trigeminal ganglionic cell in vitro and its sensitivity to infection of herpes simplex virus type 1].

We firstly report an experimental study on the sensitivity of primary cultural human trigeminal ganglionic cells infected by herpes simplex virus type 1 (HSV-1) in different time-points. The results indicate that the neuron of human trigeminal ganglia is the most sensitive cell type, the antigen of HSV-1 replicates rapidly within the cytoplasm and cell nucleus, the fibroblasts and glia cells are infected partly by the virus. Therefore, perhaps the neuron is the main harboring cell type.

Antigens, Viral↗
PubMed1993

Characterization of vascular postsynaptic NPY receptor function and regulation and differential sensitivity of Y1 and Y2 receptor function to changes in extracellular calcium availability and prior in vitro peptide exposure.

Effects of calcium-free buffer, nifedipine, or prior cumulative neuropeptide Y (NPY) receptor agonist concentration exposure on vasoconstrictive responsiveness to the agonists were assessed in norepinephrine (NE)-conditioned isolated rat femoral artery rings. Calcium-free buffer and nifedipine partially inhibited responsiveness to initial NPY exposure; residual responsiveness to NPY re-exposure was unaffected. In contrast, these treatments markedly inhibited responsiveness to the Y2 agonist NPY13-36, the calcium channel agonist BAY K 8644 (BAY) and the partial alpha 1 adrenoceptor agonist indanidine but did not alter to the Y1 agonist [Leu31,Pro34]NPY. Responsiveness to NPY and NPY13-36 but not to BAY or indanidine was markedly reduced 120 min following conditioning regardless of prior ring exposure to the same peptide; only prior exposure reduced responsiveness to [Leu31,Pro34]NPY. Responsiveness changes to NPY at various times or after various numbers of NE and/or NPY exposures indicated that pre-exposure and time-related responsiveness reductions were discriminable and temporally unrelated to conditioning. Postsynaptic vascular Y2 receptor activation therefore accounts for the known sensitivity of NPY-induced pressor and vasoconstrictive actions to nifedipine. The 'time-dependent' loss of Y2 receptor function may also explain prior failures to observe postsynaptic arterial Y2 receptors in vitro.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

An Arabidopsis thaliana lipoxygenase gene can be induced by pathogens, abscisic acid, and methyl jasmonate.

We isolated and characterized a 2.8-kb, full-length, Arabidopsis thaliana cDNA clone encoding a lipoxygenase. DNA sequence analysis showed that the deduced amino acid sequence of the Arabidopsis protein is 72 to 78% similar to that of legume seed lipoxygenases. DNA blot analysis indicated that Arabidopsis contains a single gene, LOX1, with appreciable homology to the cDNA clone. RNA blot analysis showed that the LOX1 gene is expressed in Arabidopsis leaves, roots, inflorescences, and young seedlings. LOX1 expression levels were highest in roots and young seedlings. In mature plants, LOX1 mRNA levels increased upon treatment with the stress-related hormones abscisic acid and methyl jasmonate and remained high for at least 96 h. Expression of the LOX1 gene was examined following infiltration of leaves with virulent (Psm ES4326) and avirulent (Pst MM1065) strains of Pseudomonas syringae. LOX1 mRNA levels were induced approximately 6-fold by both virulent and avirulent strains; however, the response to avirulent strains was much more rapid. Infiltration of leaves with Pst MM1065 resulted in maximal induction within 12 h, whereas maximal induction by Psm ES4326 did not occur until 48 h. When a cloned avr gene, avrRpt2, was transferred to Psm ES4326, LOX1 mRNA accumulated in a pattern similar to that observed for the avirulent strain Pst MM1065.

Abscisic Acid↗
PubMed1993

[Substance P is not involved in SII descending modulation of the nucleus centrum medianum of the thalamus in cats].

It was investigated that the effects of electrical stimulation of the somatosensory area II (SII) of the cerebral cortex and electroacupuncture on substance P (SP) concentration in the perfusate from the nucleus centrum medianum (CM) of the thalamus, in order to probe into if SP participates in the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia. Adult cats were randomly divided into three groups: control, electroacupuncture and electrical stimulation of SII. Push-pull perfusion technique was used to collect the perfusate from the nucleus CM. SP contents in the perfusate were determined by radioimmunoassay. The results showed that SP contents in the perfusate have not statistically significant changes before and after the electrical stimulation of SII or electroacupuncture, suggesting that the SP release from the nucleus CM was not influenced by the stimulation of SII or electroacupuncture. It is indicated that SP may not associate with the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia.

Acupuncture Analgesia↗
PubMed1993

[Effects of electroacupuncture at different frequencies on the nociceptive response and central contents of GABA and glutamic acid in arthritic rats].

It has been demonstrated that electroacupuncture (EA) produces analgesia in acute arthritic animal models, while the differential analgesic effects at different EA parameters remains to be discovered. In the present experiment, the effects of EA at 100 Hz and 15 Hz on bilateral Yanglingpuan acupoints of the arthritic rats was studied. The results showed: 1) 15Hz EA was more effective than 10Hz EA for analgesia; 2) spinal glutamic acid content of the 15-Hz EA group was significantly lower than that of the 100-Hz EA group, and 3) no significant difference in GABA contents between the two groups was found. The results suggest that spinal glutamic acid may be involved in the different analgesic effects of EA at different frequencies in arthritic rats.

Acupuncture Analgesia↗
PubMed1993

[The relations between acupuncture manipulations and responsive discharges of deep receptors].

Twenty-nine rabbits were used. The spindle, tendon organ, light and heavy pressure receptors in medial gastrocnemius muscle were identified by recording discharges of single afferent fiber in medial gastrocnemius nerve from fine filaments by dissection. The discharge patterns of the receptors responding to the manipulations, i.c. lift and thrust, twist and twirl, rotate, scrape flick the needle and finger-pressure were observed. Data at 85 units were collected totally. Every type of deep receptor can react to any manipulation. The discharge patterns of different receptors were alike when stimulated with same manipulation, but there were different patterns while varying manipulations acting on the same receptor. These are due to the movement forms, the force amount, the time duration of the manipulations. All these facts are nearly the same as in cutaneous receptors. Acupuncture effect on deep receptors was not limited to one point but within a certain area, namely distant effect existed. The area size varied from receptor to receptor and from manipulation to manipulation. Because of the distant effect on receptors by acupuncture, and the lose of responsibility in units when receptor destroyed, we suggest that effective acupuncture stimulation is induced mainly due to the receptor deformation, which is caused by the stress from pressure, stretch and vibration of acupuncture. In view of the needling sensation is closely related to the curative effects, the receptors dealing with needling sensation are analysed according to this series works and other facts, we further advance the opinion that the receptors of deep pain are the chief material foundation to induce the sensation of hand needling.

Acupuncture Therapy↗
PubMed1993

Characterization of vascular postsynaptic neuropeptide Y receptor function and regulation. 1. NPY-induced constriction in isolated rat femoral artery rings is mediated by both Y1 and Y2 receptors: evidence from benextramine protection studies.

Neuropeptide Y (NPY), a potent pressor agent and vasoconstrictor, is thought to contribute to the sympathetically mediated postsynaptic regulation of blood pressure primarily through activation of vascular Y1 rather than Y2 NPY receptors. However, data are available that conflict with this conclusion. In this article, the relative roles of postsynaptic Y1 and Y2 receptors as mediators of direct NPY-induced isolated rat femoral artery ring vasoconstriction were evaluated through use of selective Y1 and Y2 agonists, [Leu31, Pro34]NPY ([Leu, Pro]NPY) and NPY13-36 [NPY(13-36)], respectively, and the NPY receptor antagonist benextramine (BXT). NPY, [Leu, Pro]NPY and NPY(13-36) were equipotent as vasoconstrictors, and constriction induced by each peptide, but not by the calcium channel agonist BAY K 8644 (BAY), was almost completely blocked by 10 microM BXT. Each of the three peptides also induced self- and cross-desensitization and protection from BXT blockade, except that [Leu, Pro]NPY neither desensitized nor protected NPY(13-36)-associated responses. NPY also failed to protect [Leu, Pro]NPY- and NPY(13-36)-elicited constriction, and NPY(13-36) failed to provide self-protection, from BXT blockade. However, in these instances, as opposed to the [Leu, Pro]NPY-NPY(13-36) cross-protection experiments, the occurrence of protection was probably masked by the relatively large magnitude of desensitization concurrently induced by the protecting peptide. Taken together, the present findings suggest that NPY-induced rat femoral artery vasoconstriction is mediated by separate, BXT-sensitive, postsynaptic Y1 ([Leu, Pro]NPY-activated) and Y2 [NPY(13-36)-activated] receptors.

Animals↗
PubMed1992

Synthesis of a phenyl beta-avobioside derivative of the disaccharide component of avoparcins.

The synthesis of the phenyl beta-glycoside of avobiose, a disaccharide fragment present in the antibiotic avoparcin, is reported. It is based on glycosylation of phenyl 3,4,6-tri-O-benzyl-beta-D-glucopyranoside with 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-ribo-hex- 1-enitol, a fully protected glycal of L-ristosamine, in the presence of trimethylsilyl triflate.

Anti-Bacterial Agents↗
PubMed1992

[The relation between acupuncture manipulations and responsive discharges of cutaneous receptors].

Nine types of mechanoreceptors of hair skin in 46 rabbits were identified by recording discharges of single afferent fiber in posterior femoral cutaneous nerve from fine filaments by dissection. When seven manipulations, i.e. lift and thrust, twist and twirl, rotate, serape, flike the needle and finger-pressure were used to stimulate each receptor, their responsive discharges were observed. Data at 165 units were collected totally, 89 units in which were for the relation between manipulations and discharge patterns, and the other 76 units for discharges responding to manipulations at different distances from the receptive field. Nine types of receptors having been observed are able to respond to any acupuncture manipulations, it is thus clear that there is not any special "acupuncture receptor." Same kind of discharge pattern existed in different types of receptor when stimulated by the same acupuncture manipulation, whereas different discharge patterns can be found at the same unit when the manipulation changes. We believe that it is due to the movement form; force amount and time duration of the manipulations. Receptors responding to acupuncture were not limited to one point only, but involving a certain field surrounding the needle point. The size of this field varied with the types of receptors and kinds of manipulations. Our previous articles had reported that the acupuncture photograph leading from nerve and building on impulses induced by acupuncture and the groups of afferent fibers conducting acupuncture signals changed with different manipulations, in this paper the reasons for that have been expounded by presenting the relationship between the responsive discharges of receptors and the manipulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Therapy↗
PubMed1992

[Homology study of leptospires by molecular hybridization].

Nick translation and random primer labelling method were applied to prepare three genomic DNA probes from Leptospira interrogans strain 017, Leptospira biflexa strain Patoc I and Leptonema illini strain 3055, and then hybridized with DNA of 17 strains leptospires from different genus, species, serogroup and serovar. The results showed no homology between Leptospira and Leptonema, and only a low degree of homology between L. interrogans and L. biflexa but it showed a high degree of homology among L. interrogans. The study also proved the possibility to establish a DNA probe prepared from a single leptospira strain to detect different serovars.

Blotting, Southern↗
PubMed1992

Optimizing staff scheduling by Monte-Carlo simulation.

DOCS is a computer program which generates the staff schedule. An accounting framework is combined with an optimization technique that searches for a schedule in which all accounts are simultaneously in balance. The search is accomplished using a Monte-Carlo process which shuffles staff within the schedule. The shuffling is biased according to each staffer's account balance: the staffer who owes the most is most likely to be scheduled.

Algorithms↗
PubMed1992

[Isolation and identification of Leclercia adecarboxylate in clinical isolates in China].

1987, 3 strains of gram-negative straight rods were examined from 3 cases of patients with diarrhea. It's producing yellow pigment, fermentative metabolism of carbohydrates, oxidase test negative and motility with the help of peritrichous flagella. Through systematic biochemical identification, calculation of G+C mol% and homology of DNA/DNA, the species of Leclercia adecarboxylate are identified. While the susceptibility to certain antibiotics and the pathogenicity for white mice are tested, and relation of these microorganisms to clinical diarrhea is discussed.

Animals↗
PubMed1991

Induction of Arabidopsis defense genes by virulent and avirulent Pseudomonas syringae strains and by a cloned avirulence gene.

We developed a model system to study the signal transduction pathways leading to the activation of Arabidopsis thaliana genes involved in the defense against pathogen attack. Here we describe the identification and characterization of virulent and avirulent Pseudomonas syringae strains that elicit disease or resistance symptoms when infiltrated into Arabidopsis leaves. The virulent and avirulent strains were characterized by determining growth of the pathogen in Arabidopsis leaves and by measuring accumulation of mRNA corresponding to Arabidopsis phenylalanine ammonia-lyase (PAL), beta-1,3-glucanase (BG), and chalcone synthase (CHS) genes in infected leaves. The virulent strain, P. syringae pv maculicola ES4326, multiplied 10(5)-fold in Arabidopsis leaves and strongly elicited BG1, BG2, and BG3 mRNA accumulation but had only a modest effect on PAL mRNA accumulation. In contrast, the avirulent strain, P. syringae pv tomato MM1065, multiplied less than 10-fold in leaves and had only a minimal effect on BG1, BG2, and BG3 mRNA accumulation, but it induced PAL mRNA accumulation. No accumulation of CHS mRNA was found with either ES4326 or MM1065. We also describe the cloning of a putative avirulence (avr) gene from the avirulent strain MM1065 that caused the virulent strain ES4326 to grow less well in leaves and to strongly elicit PAL but not BG1 and BG3 mRNA accumulation. These results suggest that the Arabidopsis PAL and BG genes may be activated by distinct signal transduction pathways and show that differences in plant gene induction by virulent and avirulent strains can be attributed to a cloned presumptive avr gene.

Cloning, Molecular↗