Biomedical subjects
Publications and source records attributed to X Dong.
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.
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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)
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.
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.
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.
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.
In this experiment, the rats treated with capsaicin (50 mg/kg) s. c. on day 2 of liqe were used 12 weeks after injection. The levels of substance P(SP) in sciatic nerves and dorsal spinal cords were measured with radioimmunoassay to evaluate the extent of C-afferent fibers damaged by capsaicin. The results as follows: (1) the levels of SP in the sciatic nerve and the dorsal spinal cord are decreased by 69% and by 62% respectively, indicating the degeneration of the primary C-afferent fibers is very massive; (2) the average of basal tail-flick latency (immersing in 50 degrees C water) is prolonged 105% as compared with the control; (3) after electro-acupuncture, the average of tail-flick latency of the capsaicin treated rats is increased by 81%, while that of the vehicle treated rats increased by 54%. These data suggest that C-afferent fibers substantially mediate the transmission of noxious thermal stimuli, but is unnecessary for the transmission of acupuncture message to induce analgesia.
Condensation of crystalline methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, provided 54% of methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-alpha-L-idopyranosyluronate)-beta-D-galactopyranoside . The use of methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl trichloroacetimidate)uronate as glycosyl donor, in the presence of trimethylsilyl triflate, improved the yield to 68%. Regioselective opening of the benzylidene group with sodium cyanoborohydride followed successively by O-sulfation with the sulfur trioxide-trimethylamine complex, saponification, catalytic hydrogenolysis and selective N-acetylation gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(alpha-L-idopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside. Condensation of methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, gave methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-beta-D-galactopryano side in 85% yield. The sequence already described then gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside.
Replication of the IncFII plasmid NR1 is controlled by regulating the amount of synthesis of the repA1 initiator protein at both the transcriptional and translational levels. We have examined mutations which have altered each of these levels of regulation, resulting in different plasmid copy numbers. The genes which encode each of the individual wild-type or mutant regulatory components from the replication control region of NR1 have been cloned independently into pBR322 vectors, and their effects in trans, either individually or in various combinations, on plasmid incompatibility, stability, copy number, and repA1 gene expression have been defined.
Transcription of the repA1 gene of the IncFII plasmid NR1 is initiated at two promoters in the replication control region. Transcription from the upstream promoter is constitutive at a low level, whereas transcription from the downstream promoter is regulated. The 5' end of the constitutively synthesized transcript also encodes the transcription repressor protein for the regulated downstream promoter. Therefore, the level of the repressor protein in the cell is gene dosage dependent. Using both lac gene fusions and quantitative hybridization methods, we have determined the in vivo relationship between the rate of transcription from the regulated promoter and the repressor protein concentration as a function of gene dosage. At the wild-type copy number of NR1, transcription from the regulated promoter is 96% repressed, but substantial derepression occurs when the copy number falls below the normal value. At or above the normal plasmid copy number, the basal level of repA1 mRNA is provided by transcription from the constitutive upstream promoter.
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