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Biomedical subjects

J X Dai

Publications and source records attributed to J X Dai.

10 recordsLinked to original sources
PubMed2005

Effect of segmental artery ligation on the blood supply of the thoracic spinal cord during anterior spinal surgery: a quantitative histomorphological fresh cadaver study.

STUDY DESIGN: Human cadaver quantitative morphometric analysis of the blood vessels in the spinal cord after ligation of segmental arteries. OBJECTIVES: To investigate the effect of ligation of segmental arteries on the quantity and density of the blood vessels in the spinal cord. SUMMARY OF BACKGROUND DATA: Ligation of segmental arteries is often used in the anterior approach for correction scoliosis. However, whether or not segmental artery ligation is liable to deny the spinal cord an adequate blood supply, thus leading to paraplegia, still remains controversial. METHODS: Eleven fresh cadavers were divided into control, unilateral, and bilateral groups. For the unilateral and bilateral groups, 5 segmental vertebral arteries (T7-T11) were ligated unilaterally and bilaterally, respectively. Then, the number and density of blood vessels at different levels in the 3 groups were measured. RESULTS: Compared to that of the corresponding level in the control group, the number of blood vessels at T5 to L1 all decreased in the ligation groups. And significant differences were found at T8 (82.80 +/- 16.36), T10 (77.80 +/- 19.80), and T11 (99.20 +/- 14.85) levels, compared to those of the corresponding levels in the control group: T8 (175.80 +/- 8. 31), T9 (176.40 +/- 32. 33), T10 (171.40 +/- 9. 73), and T11 (189.20 +/- 15. 92). Further decrease was found at each corresponding level in the bilateral group, and significant differences were found at T8 (65.80 +/- 15.55), T9 (24.80 +/- 13.43), T10 (0), T11 (0), and T12 (0) levels. Similar results were obtained with regard to the density of blood vessels. Significant differences were found at T11 (1.246 +/- 0.112) and L1 (1.349 +/- 0.109) in the unilateral group, and T9 (0.260 +/- 0.088), T10 (0), T11 (0), T12 (0), and L1 (0.147 +/- 0.117) in the bilateral group compared to those of the corresponding levels in the control group: T9 (1.810 +/- 0.202), T10 (1.833 +/- 0.175), T11 (2.308 +/- 0.335), T12 (2.510 +/- 0.617), and L1 (2.193 +/- 0.033). CONCLUSIONS: This study suggests that the more levels the ligation encompasses, the higher the risk of spinal cord damage. Therefore, caution should be taken when several segmental arteries are to be ligated in the clinical setting. What is more, bilateral ligation, which is worse than unilateral ligation, can lead to a significant decrease in the number and density of blood vessels of the spinal.

Adolescent↗
PubMed2001

Molecular scaffold of a new pokeweed antifungal peptide deduced by 1H nuclear magnetic resonance.

The antifungal peptide from seeds of Phytolacca americana (Pokeweed), designated PAFP-S hereinafter, is a recently found cationic peptide which consists of 38 amino acid residues and exhibits a broad spectrum of antifungal activity, including inhibition of certain saprophytic fungi and some plant pathogens. The secondary structure and three cysteine pairings have been investigated by 1H NMR analysis. The results show that the molecular scaffold of PAFP-S features a triple-stranded antiparallel beta-sheet knotted by a typical disulfide bridge motif, which characterizes the knottin fold. CD spectroscopy indicates a high stability of the molecule in solution. Therefore, PAFP-S should be a new member of the knottin structural family and the first antifungal peptide that adopts the knottin-like fold.

Amino Acid Motifs↗
PubMed2001

Solution structure of PAFP-S: a new knottin-type antifungal peptide from the seeds of Phytolacca americana.

The three-dimensional solution structure of PAFP-S, an antifungal peptide extracted from the seeds of Phytolacca americana, was determined using 1H NMR spectroscopy. This cationic peptide contains 38 amino acid residues. Its structure was determined from 302 distance restraints and 36 dihedral restraints derived from NOEs and coupling constants. The peptide has six cysteines involved in three disulfide bonds. The previously unassigned parings have now been determined from NMR data. The solution structure of PAFP-S is presented as a set of 20 structures using ab initio dynamic simulated annealing, with an average RMS deviation of 1.68 A for the backbone heavy atoms and 2.19 A for all heavy atoms, respectively. For the well-defined triple-stranded beta-sheet involving residues 8-10, 23-27, and 32-36, the corresponding values were 0.39 and 1.25 A. The global fold involves a cystine-knotted three-stranded antiparallel beta-sheet (residues 8-10, 23-27, 32-36), a flexible loop (residues 14-19), and four beta-reverse turns (residues 4-8, 11-14, 19-22, 28-32). This structure features all the characteristics of the knottin fold. It is the first structural model of an antifungal peptide that adopts a knottin-type structure. PAFP-S has an extended hydrophobic surface comprised of residues Tyr23, Phe25, Ile27, Tyr32, and Val34. The side chains of these residues are well-defined in the NMR structure. Several hydrophilic and positively charged residues (Arg9, Arg38, and Lys36) surround the hydrophobic surface, giving PAFP-S an amphiphilic character which would be the main structural basis of its biological function.

Amino Acid Sequence↗
PubMed2000

[Construction and expression of coexpression plasmid of carcinoembryonic antigen and Newcastle disease virus HN gene].

The eukaryotic expression plasmid (pcDNA3-CEA) containing with the gene coding for the Carcinoembryonic antigen(CEA) had been gotten with RT-PCR and gene recombination techniques. Using enzymolysis, ligation and other techniques, an eukaryotic coexpression plasmid(pcDNA3-CEA/HN) containing two expression unites of CEA and Newcastle disease virus HN gene that may have the function of immunoenhancement had been constructed. The plasmid will lay a foundation for further researching CEA nucleiotide vaccine, adjuvant and their effect of special antitumor immune.

Carcinoembryonic Antigen↗
PubMed2000

[Cloning of Cysticercus cellulosae AgB cDNA coding region].

OBJECTIVE: To amplify and clone Cysticercus cellulosae AgB cDNA coding region. METHODS: The AgB cDNA was amplified by RT-PCR technique from the total RNA of Cysticercus cellulosae. It was cloned into the vector pUC118 and sequenced. RESULTS: The PCR amplified product was a single band of 2.6 kb in size. The sequences of AgB cDNA coding region has 99.8% homology with that of Australian Cysticercus cellulosae, and their amino acid sequences have 99.3% homology. CONCLUSION: Cysticercus cellulosae AgB cDNA coding region has been cloned successfully.

Animals↗
PubMed1999

Solution conformation of brazzein by 1H nuclear magnetic resonance: resonance assignment and secondary structure.

Brazzein is a sweet-tasting protein isolated from the fruit of the West African plant Pentadiplandra brazzeana Baillon. It is the smallest and the most water-soluble sweet protein discovered so far, it is also highly thermostable. The proton NMR study of brazzein at 600 MHz (pH 3.5, 300K) is presented. Complete sequence specific assignment of the individual backbone and sidechain proton resonances were achieved using through-bond and through-space connectivities obtained from standard two-dimensional NMR techniques. The secondary structure of brazzein contains one alpha-helix (residues 21-29), one short 3(10)-helix (residues 14-17), two strands of antiparallel beta-sheet (residues 34-39, 44-50) and probably a third strand (residues 5-7) near the N-terminus.

Amino Acid Sequence↗
PubMed1999

[The features of isozyme zymograms and genetic diversity in Undaria pinnatifida].

The zymogram features of 11 kinds of isozyme and gene expressions in Qingdao and Zhoushan population of U. pinnatifida gametophytes were investigated and genetic diversity was examined by PAGE (polyacrylamide gel electrophoresis) technique. The results showed that the level of genetic diversity in Qingdao population of U. pinnatifida gametophytes was higher than that in Zhoushan population. Two banding patterns controlled by two variant genes were found in alcohol dehydrogenase (Adh) of U. pinnatifida gametophytes. There were null alleles in the population.

Electrophoresis, Polyacrylamide Gel↗
PubMed1996

The role of endothelin-1 in Binswanger's disease.

BACKGROUND: Endothelin-1 is known to exist in the nervous system. A notable increase of plasma endothelin-1 is associated with acute stroke. This study was designed to measure plasma endothelin-1 levels in Binswanger's disease and explore the relationship between endothelin-1 and this disorder. METHODS: Plasma levels of endothelin-1 were-examined by radioimmunoassay in 31 patients with Binswanger's disease and in three groups of control subjects. The ratio of the plasma concentration of endothelin-1 in the internal jugular vein to that in the antecubital vein was calculated as an indicator of endothelin-1 level in cerebral circulation. RESULTS: Endothelin-1 ratio devation was seen more often in patients with Binswanger's disease than in acute stroke patients. Endithelin-1 ratios were significantly negatively correlated with Hasegawa's Dementia Scale scores is subjects with Binswanger's disease. CONCLUSIONS: Abnormalities is vasoactive factors may make an important contribution to the pathophysiology of Binswanger's disease. Endothelin-1 might be involved in the pathogenesis of this illness.

Aged↗