Biomedical subjects
Publications and source records attributed to Y L Xu.
Two new diterpenoids, forskolins I and J, have been isolated in our further investigation on Coleus forskohlii (Willd.) Briq. collected in Yunnan Province. Their structures have been determined as 1alpha,6beta-diacetoxy-7beta,9alpha-dihydroxy-8,13-epoxylabd-14-en-11-one (1) and 1alpha,9alpha-dihydroxy-6beta,7beta-diacetoxy-8,13-epoxylabd-14-en-11-one (2) by spectral methods (including 1D and 2D NMR techniques).
Two new diterpenes, forrestin H, ent-isopimaran-8 beta, 15R, 16-triol (1), forrestin I, ent-isopimaran-16-acetoxy-8 beta, 15R-diol (2) and the acetonide derivative of forrestin H were isolated from the leaves of Rabdosia forrestii. The structures were established on the basis of NMR spectroscopic analysis and of the modified Mosher's (1H) method.
BACKGROUND: ALT testing of blood donors was initiated as a surrogate marker for non-A, non-B hepatitis. Increased sensitivity of subsequent HBV and HCV tests used for standard donor screening make any residual value of ALT testing questionable. STUDY DESIGN AND METHODS: A prospective study was conducted in 166 of 645 eligible blood donors from three American Red Cross regions whose ALT was > or =120 IU per L and whose standard donor screening tests were negative. Of these enrolled donors, 124 (75%) completed follow-up. Samples obtained from the index donation, at enrollment (1 month), and at follow-up (6 months) underwent the standard donor screening tests, as well as those for HCV RNA and HGV RNA (RT-PCR), antibodies to the virus envelope E2 protein of GB virus type C (GBV-C E2 antibody), and IgM antibody for CMV, parvovirus B19, EBV VCA, and HAV. Participants completed a brief demographic and exposure history questionnaire at follow-up. RESULTS: All study samples were negative in standard donor-screening tests. ALT levels were variable at return visits, with 80 to 86 percent <120 IU per L. No participants were positive for HCV RNA; 4 percent were positive for HGV RNA, and 10 percent were positive for GBV-C E2 antibody. Results of CMV, parvovirus B19, EBV VCA, and HAV testing were similar to published background rates. No demographic or exposure history variables had significant correlation with ALT or other testing results. CONCLUSION: These data suggest that an ALT > or =120 IU per L in blood donors with negative standard screening tests has questionable value as a surrogate marker for seronegative HBV or HCV infection. Continued ALT testing may contribute little, if anything, to the safety of blood components or plasma for further manufacture.
OBJECTIVE: To screen the mimic antigen epitopes of the triose phosphate isomerase of Schistosoma japonicum Chinese strain (SjC-TPI) and investigate their immunogenicity. METHODS: The random phage peptide library (PH.D.-12) was screened with the purified antibody(IgG) against SjC-TPI to get the positive phage which contained the mimic antigen epitopes of SjC-TPI, and the immuno-characterization of the mimic antigen epitopes were investigated. RESULTS: Two mimic antigen epitopes (M1, M2) of SjC-TPI were obtained. The immuno-sera of mice (Kunming strain) against the positive phages could recognize both the SjC-TPI and the protein of the positive phages. The DNA sequencing data showed no homology between the sequences of the deduced amino acid of the two mimic antigen peptides and the amino acid of SjC-TPI. CONCLUSION: The two mimic antigen epitopes of SjC-TPI obtained are imitative epitopes of the configuration antigen of SjC-TPI.
OBJECTIVE: To develop 23 kDa membrane protein DNA vaccine of Schistosoma japonicum Chinese strain and test its protective efficacy in infected C57BL/6 mice. METHODS: The full length cDNA encoding SjC23 amplified from pUC19-SjC23 subcloned into pcDNA3.1. 48 female mice were divided into three groups: A, B and C. Group A (control group) was each immunized i.m. with 100 micrograms of pcDNA3.1; group B (SjC23 group) was each immunized i.m. with 100 micrograms of pcDNA3.1-SjC23; group C (SjC23 + IL-12) was each immunized i.m. with a mixture of 100 micrograms of pcDNA3.1-SjC23, 100 micrograms of pcDNA3.1-p35 and 100 micrograms of pcDNA-p40, followed by two boosts of the same DNA once every two weeks. All the mice were challenged with 45 cercariae at week 8, killed and perfused for worms at week 14. The expression of SjC23 and p35, p40 in muscle tissue was determined by immuno-histochemical method. By the culture of spleen cells, the production of IL-2, IL-4, IL-10 and IFN-gamma after the stimulation of rSjC23-HD was determined two weeks before and after challenge. Anti-SjC23 antibodies were tested by Western blotting. RESULTS: SjC23 and p35, p40 were all expressed on the membrane and in the plasma of muscle cells of the infected mice. Significant increase of IL-2 and IFN-gamma in SjC23 and SjC23 + IL-12 groups was observed before and after challenge. Western blotting showed that after the third immunization (before challenge) 8 out of 10 sera from SjC23 group and 9 out of 10 sera from SjC23 + IL-12 group were positive. The worm reduction rate in SjC23 group and SjC23 + IL-12 group was 26.9% and 35.4%, respectively; the number of eggs in liver tissue was reduced by 22.2% and 28.4%, respectively. CONCLUSION: pcDNA3.1-SjC23 DNA vaccine could induce partial protection against Schistosoma japonicum in C57BL/6 mice.
OBJECTIVE: This article discusses the anatomy, surgical procedure,indication, advantages and disadvantages of the submental island flap in reconstruction of the defects after head and neck tumor surgery, based on our clinical experience. METHODS: The submental island flap was transferred with the submental vessels(A/V) as pedicle. In harvesting the flap, the flap was raised commencing from the contralateral side, dissecting all tissues off the mylohyoid muscles. Submandibular triangle dissection was taken until the facial artery and the facial vein. Then the submandibular gland and submandibular nodes were removed and submental vessels were left. This produces a large skin paddle which can be tunnelled to its recipient site. RESULTS: From Aug. 1998 to Oct. 1999, 16 submental island flaps were performed in our department. 15 flaps survived well and 1 flap failed, with a success rate of 15/16 (93.8%). CONCLUSION: The submental island flap is appropriate for primary reconstruction of the defect after various head and neck tumor surgery. It has a long and reliable pedicle, rapid and simple to raise and free from vessel anastomosis. It leaves a well hidden donor site. However, it can't be applied to these cases whose donor site had been radiated before surgery and whose submental and submandibular triangles lymph nodes were positive.
We present theoretical results for the source function in photophoresis of an arbitrary aggregate of spheres that are homogeneous and isotropic piecewise. This source function directly represents the distribution of electric fields inside the spheres. Our calculation is based on a rigorous analytic solution to the radiative multisphere-scattering problem developed recently [Y.-l. Xu, Appl. Opt. 34, 4573 (1995); 36, 9496 (1997); Phys. Lett. A 249, 30 (1998)]. When an aggregate degenerates to a single sphere, the results are exactly the same as those given by the Mie theory. We also discuss the numerical techniques necessary for obtaining an accurate numerical solution for the source function.
The gibberellin (GA) 20-oxidase encoded by the GA5 gene of Arabidopsis directs GA biosynthesis to active GAs, whereas that encoded by the P16 gene of pumpkin endosperm leads to biosynthesis of inactive GAs. Negative feedback regulation of GA5 expression was demonstrated in stems of Arabidopsis by bioactive GAs but not by inactive GA. In transgenic Arabidopsis plants overexpressing P16, there was a severe reduction in the amounts of C20-GA intermediates, accumulation of large amounts of inactive GA25 and GA17, a reduction in GA4 content, and a small increase in GA1. However, due to feedback regulation, expression of GA5 and GA4, the gene coding for the subsequent 3beta-hydroxylase, was greatly increased to compensate for the effects of the P16 transgene. Consequently, stem height was only slightly reduced in the transgenic plants.
Hepatitis C virus testing has evolved from a simple enzyme-linked immunosorbent assay (ELISA) to complex molecular tests including qualitative and quantitative polymerase chain reaction (PCR) as well as multiple methods to determine geno and serotypes. Serotyping assays have been described and are being further refined to aid describing the epidemiology of hepatitis C virus (HCV) infection and may have a role in predicting response treatment. This study describes the concordance between two serotyping assay systems, a recombinant immunoblot assay Chiron RIBA Strip Immunoblot Assay (SIA) and a more competitive ELISA peptide assay, using PCR as the standard. Serotype was successfully determined in 144/202 (71%) patients by the Murex ELISA assay and 179/202 (89%) by the Chiron strip immunoblot assay (SIA) assay (P < 0.001). Concordance between restriction fragment length polymorphism (RFLP) and the Murex assay was 139/144 (97%) between RFLP and the Chiron SIA was 171/179 (96%) and between the Murex and Chiron SIA was 136/144 (94%). These assays provided a reliable, simple, and rapid method of determining HCV serotype.
Arabidopsis thaliana (L.) Heynh. is a quantitative long-day (LD) rosette plant in which stem growth is mediated by gibberellins (CAs). Application of GAs to plants in short-day (SD) conditions resulted in rapid stem elongation and flower formation, with GA4 and GA9 being equally effective, and GA1 showing lower activity. The effects of photoperiod on the levels of endogenous GAs were measured by combined gas chromatography-mass spectrometry with selected ion monitoring. When plants were transferred from SD to LD conditions there was a slight decrease in the level of GA53 and an increase in the levels of C19-GAs, GA9, GA20, GA1, and GA8, indicating that GA 20-oxidase activity is stimulated in LD conditions. Expression of GA5, which encodes GA 20-oxidase, was highest in elongating stems and was correlated with the rate of stem elongation. By contrast, GA4, which encodes 3 beta-hydroxylase, showed low expression in stems and its expression was not correlated with the rate of stem elongation. We conclude that stem elongation in LD conditions is at least in part due to increased expression of GA5, whereas expression of GA4 is not under photoperiodic control.
The epithelial cells of the lower respiratory tract are exposed to high levels of inhaled oxygen and other oxidants. We hypothesized that lung cells would secrete the antioxidant enzyme, extracellular glutathione peroxidase (eGPx), into epithelial lining fluid (ELF). To investigate this hypothesis, we used specific immunoprecipitations of GPx enzymes from ELF, specific immunoprecipitations of 75Se metabolically labeled proteins from lung cells in culture, and in situ hybridization, Northern blot, and reverse transcription-polymerase chain reaction (RT-PCR) analyses. Fifty-seven percent of ELF GPx activity was due to eGPx and 40% was due to cellular GPx (cGPx). Primary bronchial epithelial cells (BEC), primary alveolar macrophages (AM), and two human bronchial epithelial cell lines, BEP2D and A549, synthesized both eGPx and cGPx and secreted eGPx into the medium. Freshly isolated human AM and BEC expressed eGPx mRNA, while freshly isolated rabbit type 2 pneumocytes did not. In lung tissue, eGPx mRNA was found mainly in interstitial cells of tissue surrounding airways. It is concluded that more than half of GPx activity in BAL is due to eGPx, and that BEC, AM, and interstitial cells are potential sources of pulmonary eGPx.
51 nurses in the out patient department (OPD) were surveied by Eysenck Personality Questionaire and Cattle 16 Personality Factors. Some nurses' jobs were changed and the psychological principles were applied to improve the nurses' mental health by the manager according to the result. The management in the out patient department was more effective after behavior theory was adopted.
The biosynthesis of gibberellins (GAs) after GA12-aldehyde involves a series of oxidative steps that lead to the formation of bioactive GAs. Previously, a cDNA clone encoding a GA 20-oxidase [gibberellin, 2-oxoglutarate:oxygen oxidoreductase (20-hydroxylating, oxidizing), EC 1.14.11.-] was isolated by immunoscreening a cDNA library from liquid endosperm of pumpkin (Cucurbita maxima L.) with antibodies against partially purified GA 20-oxidase. Here, we report isolation of a genomic clone for GA 20-oxidase from a genomic library of the long-day species Arabidopsis thaliana Heynh., strain Columbia, by using the pumpkin cDNA clone as a heterologous probe. This genomic clone contains a GA 20-oxidase gene that consists of three exons and two introns. The three exons are 1131-bp long and encode 377 amino acid residues. A cDNA clone corresponding to the putative GA 20-oxidase genomic sequence was constructed with the reverse transcription-PCR method, and the identity of the cDNA clone was confirmed by analyzing the capability of the fusion protein expressed in Escherichia coli to convert GA53 to GA44 and GA19 to GA20. The Arabidopsis GA 20-oxidase shares 55% identity and > 80% similarity with the pumpkin GA 20-oxidase at the derived amino acid level. Both GA 20-oxidases share high homology with other 2-oxoglutarate-dependent dioxygenases (2-ODDs), but the highest homology was found between the two GA 20-oxidases. Mapping results indicated tight linkage between the cloned GA 20-oxidase and the GA5 locus of Arabidopsis. The ga5 semidwarf mutant contains a G-->A point mutation that inserts a translational stop codon in the protein-coding sequence, thus confirming that the GA5 locus encodes GA 20-oxidase. Expression of the GA5 gene in Ara-bidopsis leaves was enhanced after plants were transferred from short to long days; it was reduced by GA4 treatment, suggesting end-product repression in the GA biosynthetic pathway.
The pattern of high mobility group proteins 1 and 2 (HMG1,2) interaction with the 5'-flanking sequence of the human beta-globin gene has been analyzed by scanning tunnelling microscopy (STM). A 200 bp negative regulatory region in the 5'-flanking sequence of the human beta-globin gene can be folded by HMG proteins 1 and 2 into a circular structure (diameter 70 +/- 6 A) with a linear tail which seems to be a left-handed double helix structure.
Using scanning tunnelling microscopy, we have directly observed parallel stranded DNA helixes of 43 nucleotides in length. The double helix is right-handed and has an average spacing, 17.43 A (+/- 1 S.D.: 2.30 A), and an average apparent depth, 4.79 A (+/- 1 S.D.: 1.04 A) for each groove. The average pitch of the helical turn is 34 A (+/- 1 S.D.: 3.35 A) and consists of no more than ten base pairs. The diameter of the helix is approx. 17-20 A. Our results provide direct evidence for the existence of a parallel structure of DNA in vitro and some details of its fine structure.
We have examined the mechanisms by which tumor cells bind to endothelial cells utilizing cultured melanoma cells and microvascular endothelial cells derived from human dermis (HDMEC). The ability of biologic response modifiers (BRM) to modulate the adhesion of melanoma cells to HDMEC was defined and those results were compared with results from human umbilical vein endothelial cells (HUVEC). SK-MEL-2, WM266-4, and Hs 294T melanoma cells all bound to HDMEC and HUVEC monolayers and adherence of melanoma cells was enhanced in a dose- and time-dependent manner by the treatment of HDMEC with interleukin 1 (IL-1) alpha or tumor necrosis factor (TNF) alpha. Similar increases in binding to HDMEC or HUVEC were induced after BRM stimulation, although baseline melanoma cell binding to HUVEC tended to be slightly higher than to HDMEC. In contrast, whereas phorbol 12-myristate 13-acetate (PMA) augmented melanoma cell adherence to HDMEC, PMA failed to increase adherence to HUVEC. The alterations in melanoma cell binding were induced only after pretreatment of endothelial and not melanoma cells with PMA. Studies of the expression of cell adhesion molecules (CAM) on HDMEC and HUVEC using enzyme-linked immunosorbent assay showed that vascular cell adhesion molecule 1 (VCAM-1) is not induced by PMA on HDMEC and intercellular adhesion molecule 1 (ICAM-1) is downregulated on HDMEC by PMA treatment. Endothelial leukocyte adhesion molecule 1 (ELAM-1) is induced by PMA, IL-1 alpha, or TNFalpha, but its expression does not correlate with increased melanoma cell binding MoAb recognizing VCAM-1-inhibited TNFalpha-induced increases in melanoma cell binding to HUVEC. However, anti-VCAM-1 antibody failed to clock melanoma cell binding to PMA or IL-1 alpha-stimulated HDMEC and only partially inhibited melanoma cell binding to TNF alpha-stimulated HDMEC. This study demonstrates that PMA and IL-1 alpha-induced increases in melanoma cell adherence to HDMEC are not mediated via known CAM, including ICAM-1, VCAM-1, or ELAM-1, and may be affected through microvessel-specific novel proteins not previously described on endothelial cells.
Human infants are relatively resistant to Clostridium difficile-associated diarrhea and colitis compared to adults. In that toxin A is the major cause of intestinal damage with this organism, we compared toxin A receptor binding and biological effects in newborn vs adult rabbit ileum. Purified toxin A (M(r) 308 kD) was labeled with tritium or biotin with full retention of biologic activity. Appearance of specific toxin A brush border (BB) binding was strongly age dependent with minimal [3H]toxin A specific binding at 2 and 5 d of life, followed by gradual increase in binding to reach adult levels at 90 d. Absence of toxin A binding sites in newborn and presence in adult rabbits was confirmed by immunohistochemical studies using biotinylated toxin A. Toxin A (50 ng to 20 micrograms/ml) inhibited protein synthesis in 90-d-old rabbit ileal loops in a dose-dependent fashion. In contrast, inhibition of protein synthesis in 5-d-old rabbit ileum occurred only at the highest toxin A doses (5 and 20 micrograms/ml) and at all doses tested was significantly less than the adult rabbit ileum. In addition, toxin A (5 micrograms/ml) caused severe mucosal damage in adult rabbit ileal explants but had no discernable morphologic effect on 5-d-old rabbit intestine. Our data indicate that newborn rabbit intestine lacks BB receptors for toxin A. The absence of the high-affinity BB receptor for toxin A in the newborn period may explain lack of biologic responsiveness to purified toxin, and the absence of disease in human infants infected with this pathogen.
Gastric, hepatic, and pulmonary cancer cell lines, and the third passage of normal gastric and pulmonary cell lines were analyzed by proton induced X-ray emission (PIXE) method. The contents of element Sr, Ca, Fe, Zn, P, K, Cu, and As in the cell lines were determined. The Sr, Ca, Fe, Zn, and As contents in cancer cell lines were significantly lower than those in the normal cell lines (p less than 0.05), whereas there were no significant differences for the P, K, and Cu contents (p greater than 0.1). The results suggest that the need of some essential elements has been diminished in cancer cell proliferation.