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J Yang

Publications and source records attributed to J Yang.

At least 109 records · Page 6Linked to original sources
PubMed2004

Origin and evolution of the light-dependent protochlorophyllide oxidoreductase (LPOR) genes.

Light-dependent NADPH-protochlorophyllide oxidoreductase (LPOR) is a nuclear-encoded chloroplast protein in green algae and higher plants which catalyzes the light-dependent reduction of protochlorophyllide to chlorophyllide. Light-dependent chlorophyll biosynthesis occurs in all oxygenic photosynthetic organisms. With the exception of angiosperms, this pathway coexists with a separate light-independent chlorophyll biosynthetic pathway, which is catalyzed by light-independent protochlorophyllide reductase (DPOR) in the dark. In contrast, the light-dependent function of chlorophyll biosynthesis is absent from anoxygenic photosynthetic bacteria. Consequently, the question is whether cyanobacteria are the ancestors of all organisms that conduct light-dependent chlorophyll biosynthesis. If so, how did photosynthetic eukaryotes acquire the homologous genes of LPOR in their nuclear genomes? The large number of complete genome sequences now available allow us to detect the evolutionary history of LPOR genes by conducting a genome-wide sequence comparison and phylogenetic analysis. Here, we show the results of a detailed phylogenetic analysis of LPOR and other functionally related enzymes in the short chain dehydrogenase/reductase (SDR) family. We propose that the LPOR gene originated in the cyanobacterial genome before the divergence of eukaryotic photosynthetic organisms. We postulated that the photosynthetic eukaryotes obtained their LPOR homologues through endosymbiotic gene transfer.

Amino Acid Sequence↗
PubMed2004

Cytotoxic and topographical properties of 6-arylidene-2-dimethylaminomethylcyclohexanone hydrochlorides and related compounds.

A number of 2-arylidenecyclohexanones (1a-h) were converted into the corresponding Mannich bases (2a-h) and (3a,f). Evaluation against murine L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes revealed the marked cytotoxicity of the Mannich bases and also the fact that almost invariably these compounds were more potent than the precursor enones (1a-h). Further evaluation of most of the Mannich bases towards a panel of nearly 60 human tumour cell lines confirmed their utility as potent cytotoxins. In this assay, the compounds showed growth-inhibiting properties greater than the anticancer alkylator melphalan. QSAR studies revealed that in some cell lines compounds possessing small electron-attracting aryl substituents showed the greatest potencies. Molecular modeling and X-ray crystallography demonstrated that various interatomic distances and torsion angles correlated with cytotoxicity. A representative compound (2a) demonstrated weak inhibiting properties towards human N-myristoyltransferase and stimulated a tyrosine protein kinase. A single dose of 100 mg/kg of most of the compounds did not prove to be lethal in mice.

Acyltransferases↗
PubMed2004

Torque properties of a rat oesophagus for physiological and diabetic conditions.

In this paper the torque of an oesophagus is studied for physiological and diabetic conditions. Since the function of the oesophagus is mainly mechanical, this work is focused on providing quantitative measurement of the passive biomechanical properties of the oesophagus torque. The oesophagus was treated as a membrane when calculating the stress and strain. The torque versus twist-angle relation was approximated to be linear at a specified pressure and longitudinal stretch ratio. Thus, the shear modulus can be computed by the torque, twist angle and polar moment of inertia in this state. The shear modulus varies greatly with the changing inflation pressure and longitudinal stretch ratio. When the longitudinal stretch ratio or transmural pressure is constant, the shear modulus is increased after 28 days of diabetes.

Animals↗
PubMed2004

B-Lymphocytes activated by CD40 ligand induce an antigen-specific anti-tumour immune response by direct and indirect activation of CD8(+) T-cells.

In this report, we describe the ability of CD40-ligand (CD40L)-activated, antigen-loaded B-cells to initiate antigen-specific anti-tumour immune responses in vivo. Mice immunized by means of intravenous administration of CD40L-activated B-cells loaded with an MHC class-I-binding peptide, and challenged with a tumour cell line expressing the same class-I epitope, showed a marked delay in tumour growth, compared to non-immunized controls or to mice receiving either freshly isolated B-cells or B-cells activated with lipopolysaccharide or interleukin-4. The ability of CD40L-activated B-cells to induce antigen-specific T-cell activation appeared to be through a combination of cross-presentation of antigen from activated B-cells to resident antigen-presenting cells and direct T-cell activation by the administered B-cells themselves. Immunization with CD40L-activated B-cells may, therefore, represent a means by which to stimulate anti-tumour CD8(+) T-cell responses in vivo.

Animals↗
PubMed2004

Adenosine A receptors are necessary for protection of the murine heart by remote, delayed adaptation to ischaemia.

AIMS: Adenosine is involved in classic pre-conditioning (PC) in most species, acting through especially adenosine A1 and A3 receptors. We studied whether the adenosine A1 receptor (A1R) was important for remote, delayed adaptation to ischaemia using a mouse with targeted deletion of the A1R gene. METHODS: Remote, delayed adaptation was evoked by brain ischaemia (BIPC) through bilateral ligation of the internal carotid arteries. Through microdialysis probes placed in the brain and the abdominal aorta, we found that plasma adenosine increased following carotid artery ligation. Twenty-four hours after ligation, hearts were isolated, Langendorff perfused and subjected to 40 min global ischaemia and 60 min reperfusion. Hearts from sham operated and BIPC animals either with (A1R+/+) or without (A1R-/-) the gene for the adenosine A(1)R were compared with each other. RESULTS: In wild types, BIPC reduced infarct size and improved functional recovery during reperfusion, but BIPC did not protect hearts of A1R-/- mice. There were no significant differences between sham-operated A1R+/+ and A1R-/- in recovery of function or infarct size. The mitogen-activated protein kinases (MAPKs) extracellular signal-regulated protein kinase1/2 (ERK1/2), p38 and c-jun N-terminal kinase (JNK) were phosphorylated during reperfusion of sham treated hearts. The increase in ERK1/2 and p38 phosphorylation detected was attenuated in hearts of BIPC or A1R-/- animals. CONCLUSION: During BIPC adenosine acting on the A1R appears necessary for myocardial protection. MAPK signalling may possibly be involved in organ protection during the delayed phase of remote, delayed adaptation.

Adaptation, Physiological↗
PubMed2004

The genetic epidemiology of alopecia areata in China.

BACKGROUND: Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease with genetic predisposition and an environmental trigger. There are few clinical data in Asians. OBJECTIVES: To describe the genetic epidemiological features of AA patients in China and to determine the possible genetic model for AA. METHODS: Data for 1032 patients with AA were obtained by questionnaire in the Institute of Dermatology of Anhui Medical University in China from 2001 to 2003. Complex segregation analysis and heritability analysis were performed using Falconer's method, EPI INFO 6.0 and SAGE-REGTL programs. RESULTS: In total, 1032 AA patients (male/female ratio 1.1 : 1) were enrolled, representing 0.94% of the total number of cases seen in our outpatient clinic during that time. The mean +/- SD age of onset was 28.98 +/- 13.43 years. The difference between the mean age of onset in males and females was not significant. Most patients (82.6%) experienced their first episode of AA within the first four decades of life. A positive family history of AA was obtained in 87 patients (8.4%). The prevalence of AA in first-, second- and third-degree relatives of the proband with AA was 1.6%, 0.19% and 0.03%, respectively. These figures were higher than those in controls. A greater severity and longer duration of AA were seen in the early onset group than in the late-onset group. The early onset group also had more affected first- and second-degree relatives. The heritability of AA in first-, second- and third-degree relatives was 47.16%, 42.53% and 22.29%, respectively. Based on the REGTL results, the best model was a polygenic additive model for AA. CONCLUSIONS: The effect of genetic factors is strong in AA, but environmental factors such as infection and psychological stress may still play an important role. Our findings on the genetics of AA are consistent with a polygenic additive mode of inheritance.

Adolescent↗
PubMed2004

Haplotype associations of the MHC with psoriasis vulgaris in Chinese Hans.

Summary Haplotype associations of the major histocompatibility complex (MHC) with psoriasis vulgaris (PV) have been demonstrated in different racial or ethnic populations. The objective of this study was to demonstrate the different haplotype associations of the MHC in Chinese patients with psoriasis according to the type of onset and their sex. One hundred and thirty-eight patients with PV and 149 normal control subjects without psoriasis were typed for HLA-A, -B, -C, -DQA1, -DQB1 and -DRB1 by using the PCR with sequence-specific primers. The results showed: (i) HLA-A*26 (26.1% vs. 12.1%, Pc < 1 x 10(-5)), -B*27 (17.03% vs. 1.01%, Pc < 1 x 10(-7)), -Cw*0602 (15.58% vs. 5.03%, Pc < 1 x 10(-2)), -DQA1*0104 (19.93% vs. 9.40%, Pc < 1 x 10(-3)), -DQA1*0201 (22.40% vs. 10.74%, Pc < 1 x 10(-3)), -DQB1*0303 (18.12% vs. 9.73%, Pc < 1 x 10(-7)), and -DRB1*0701/02 (26.09% vs. 9.73%, Pc < 1 x 10(-7)) were significantly increased in PV patients, while HLA-B*57, -DQB1*0201 were slightly increased in PV patients. HLA-Cw*0304 (5.07% vs. 14.43%, Pc < 1 x 10(-3)), -DQA1*0501 (5.79% vs. 14.09%, Pc < 0.05) were found to be negatively associated with PV, but HLA-A*2 (2.54% vs. 6.38%, Pc < 0.5) was decreased in PV patients without statistical significance. (ii) HLA-A*26-B*27 [P < 0.0001, odds ratio (OR) = 48.38], -A*26-Cw*0602 (P < 0.0001, OR = 11.84), -B*27-Cw*0602 (P < 0.0001, OR = undefined), -DRB1*0701/02-B*27 (P < 0.0001, OR = 22.62), -DRB1*0701/02-DQA1*0104 (P < 0.0002, OR = 3.59), -DRB1*0701/02-DQB1*0303 (P < 0.0001, OR = 5.63), -DQA1*0201-DQB1*0303 (P < 0.0002, OR = 7.77), -A*26-B*27-Cw*0602 (P < 0.0004, OR = undefined), -A*26-DRB1*0701/02-DQA1*0201-DQB1*0303 (P < 0.01, OR = undefined) were identified as risk haplotypes for patients with PV in China. (iii) HLA-A*26 -B*27 (P < 0.0001, OR = 58.47), -DQA1*0201-DQB1*0303 (P < 0.0001, OR = 8.62), -DRB1*0701/02 -DQA1*0104 (P < 0.0002, OR = 4.13), -DRB1*0701/02-DQB1*0303 (P < 0.0001, OR = 6.68) and -A*26-DRB1*0701-DQA1*0201 -DQB1*0303 (P < 0.006, OR = undefined) were only significantly associated with type I psoriasis compared with controls, while others showed no differences in either type I or type II psoriasis. (iv) These associated haplotypes with PV were not different by sex, except that the frequency of DRB1*0701/02-DQB1*0303 (P < 0.0001, OR = 10.14) was higher in male patients with psoriasis. To summarize, this study demonstrated a differential association of HLA and identified some special risk haplotypes in Chinese patients with PV compared with other ethnic or racial populations.

Adolescent↗
PubMed2004

Biomechanical properties of the rat oesophagus in experimental type-1 diabetes.

The gastrointestinal tract remodels its morphology and circumferential stress-strain properties in diabetes mellitus. This study adds one more piece of mechanical knowledge, namely the oesophageal shear modulus and its dependence on the circumferential and longitudinal stresses and strains of oesophagus in diabetic rats and control rats. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg kg(-1) body weight). The diabetic rats lived up to 28 days after the induction of diabetes. The oesophagus was studied in vitro using a triaxial machine. Stepwise elongation and inflation plus continuous twist were carried out with measurement of the resultant forces. Circumferential and longitudinal stresses and strains were computed from steady-state values of longitudinal force, outer diameter and the applied pressure. The shear modulus was computed from the twist angle-torque relationship. The circumferential and longitudinal stress-strain relationships were exponential. The circumferential stiffness increased 1 week after induction of diabetes (P < 0.001). The longitudinal stiffness increased in the 4-week diabetic rats (P < 0.001). The shear modulus varied as function of longitudinal strain and pressure. The oesophagus became stiffer in shear 4 weeks after the induction of diabetes (P < 0.001).

Animals↗
PubMed2004

Specific serum IgE levels and FcepsilonRIbeta genetic polymorphism in patients with penicillins allergy.

BACKGROUND: Numerous studies have suggested that both genetic and environmental influences are involved in the pathogenesis of allergic disease and atopy. The objective of this investigation is to elucidate the underlying mechanism of penicillins allergy and improve the diagnostic methods. METHODS: Radioallergosorbent test was used to examine eight kinds of specific IgE antibodies, which included four kinds of major and minor antigenic determinants, respectively, in the sera of 448 patients with penicillins allergy and 101 healthy subjects. A restriction endonuclease fragment length polymorphism of a polymerase chain reaction product was used for analysis of the FcepsilonRIbeta polymorphism. RESULTS: The positive rate of specific IgE in 448 patients was 58.26% (261), in which 37.28% (167) patients had positive IgE to major antigenic determinants and 47.09% (211) patients had positive IgE to minor antigenic determinants. Of the 179 patients with allergic history, 70.83% (17/24) patients had positive antibodies within 30 days, while 45.28% (24/53) had positive antibodies after 5 years. The positive reaction degree of skin test was absolutely correlated with specific IgE (P=0.047). Among patients with positive specific IgE, significant differences of E237G genotype were observed between patients with positive benzylpenicillanyl (BPA)-, phenoxomethylpenicilloyl (PVO)- or ampicilloyl (APO)-IgE and control group (P=0.015, 0.015, and 0.008, respectively). There were significant differences in E237G genotype between positive and negative BPA-, PVO- as well as APO-IgE patients (P = 0.014, 0.02, and 0.011, respectively). CONCLUSIONS: The patients with penicillins allergy have positive specific IgE not only to major antigenic determinants but also to minor antigenic determinants. The E237G variant of the FcepsilonRIbeta gene is involved in the development of penicillins allergy through the process for the production of specific IgE antibodies.

Adolescent↗
PubMed2004

Clinical implementation of intensity-modulated tangential beam irradiation for breast cancer.

A Monte Carlo based intensity-modulated radiation therapy (IMRT) treatment planning system has been developed and used for breast treatment. An iterative method was used for optimization to generate IMRT plans and a step-and-shoot technique was used for beam delivery. The patient setup and incident beam directions were the same as those for conventional tangential photon treatment. The weights for the opposed beamlets in the two tangential beams were determined first by the doses at the depths of the maximum dose at both sides to minimize hot spots. The intensity of an individual beamlet pair was then optimized based on the dose at the midplane. Fine tuning was made to achieve optimal target dose uniformity and to reduce the dose to the heart when necessary. The final dose calculations were performed using the Monte Carlo method and the plans were verified by phantom measurements. The dose distributions and dose-volume-histograms of IMRT plans were compared with those of conventional plans that were generated using a commercial treatment planning system and recalculated using an in-house Monte Carlo system for the first 25 patients. The dose comparisons showed that the percentage volume receiving more than 95% of the prescription dose (V95) and the percentage volume receiving more than 100% of the prescription dose (V100) for the clinical target volume (CTV) of IMRT plans were about the same as those of conventional plans. The percentage volume receiving more than 105% of the prescription dose (V105) for the CTV was reduced from 23.1% to 7.9% on average. The percentage volume of the lung receiving more than 20 Gy dose (V20 Gy) during the entire treatment was reduced by about 10%. The percentage volume of the heart receiving more than 30 Gy dose (V30 Gy) is reduced from 3.3% to 0.3%. Further studies revealed that a less than 5 degrees change in couch angle and collimator angle at patient setup had no significant effect on the dose coverage of CTV but had significant effect on the dose to the lung and heart. The study on the effect of beam spoiler showed that it increased the dose at the buildup region by 0- 13% that varies with location. The machine output linearity and stability for small monitor unit delivery of Siemens accelerators used for this study was checked and found to be suitable for breast IMRT. The total effect of variations was calculated to be less than 1% for typical breast treatments. The beam delivery time was increased by about 2 min compared with conventional tangential treatments. The whole treatment including patient setup and beam delivery can be completed in a 15 min slot. The IMRT technique has been proven practical for breast treatment clinically. The results showed that tangential IMRT improved the dose homogeneity in the breast and reduced the dose to the lung and heart.

Algorithms↗
PubMed2004

Role of RepA and DnaA proteins in the opening of the origin of DNA replication of an IncB plasmid.

The replication initiator protein RepA of the IncB plasmid pMU720 was shown to induce localized unwinding of its cognate origin of replication in vitro. DnaA, the initiator protein of Escherichia coli, was unable to induce localized unwinding of this origin of replication on its own but enhanced the opening generated by RepA. The opened region lies immediately downstream of the last of the three binding sites for RepA (RepA boxes) and covers one turn of DNA helix. A 6-mer sequence, 5'-TCTTAA-3', which lies within the opened region, was essential for the localized unwinding of the origin in vitro and origin activity in vivo. In addition, efficient unwinding of the origin of replication of pMU720 in vitro required the native positioning of the binding sites for the initiator proteins. Interestingly, binding of RepA to RepA box 1, which is essential for origin activity, was not required for the localized opening of the origin in vitro.

Bacterial Proteins↗
PubMed2004

Mandibular bone remodelling in adults: evaluation of panoramic radiographs.

OBJECTIVES: To evaluate the changes in the antegonial angle, antegonial depth and gonial angle in edentulous and dentate patients in different age groups and between genders. METHODS: We evaluated 312 panoramic radiographs selected from our files. The images were grouped into four 10-year age groups (by decades). The youngest age group was 40-49 years and the oldest 70-79 years. Gender, dentition status and age were recorded. Measurements were made by two observers. RESULTS: No significant differences were observed for the gonial angle regarding age, gender and edentulism. For antegonial angle, the males (160.86 degrees +/-0.78) had significantly smaller values than females (165.08 degrees +/-0.58) irrespective of the dental status (P<0.0001). Edentulous individuals (161.51 degrees +/-0.83) had a smaller antegonial angle than dentate (165.05 degrees +/-0.76) and partially dentate (163.81 degrees +/-0.81) individuals (P<0.05). The antegonial depth was significantly greater for males than females (2.12 mm+/-0.09 vs 1.46 mm+/-0.07, P<0.0001). Edentulous individuals (1.87 mm+/-0.1) had significantly greater antegonial depth than dentate and partially dentate individuals (1.60 mm+/-0.1 and 1.65 mm+/-0.1, respectively). CONCLUSION: The gonial angle did not show any change with gender, age and dental status whereas the antegonial region had a resorptive pattern in the edentulous mandible. The morphology of the antegonial region was influenced by gender and dental status.

Adult↗
PubMed2004

Telomerase activation by Epstein-Barr virus latent membrane protein 1 is associated with c-Myc expression in human nasopharyngeal epithelial cells.

Latent membrane protein 1 (LMP1), one of the oncoproteins encoded by Epstein-Barr virus is sufficient for the development of nasopharyngeal carcinoma in vivo and nasopharyngeal epithelial cellular immortalization in vitro. It has also been shown to increase the telomerase activity in primary human nasopharyngeal epithelial cells by an unknown mechanism. We reported here that LMP1 could increase telomerase activity in coordination with LMP1-induced c-Myc expression in LMP1-transfected primary human nasopharyngeal epithelial cells or in a dual-stable LMP1 integrated nasopharyngeal carcinoma cell line with Tet-on regulatory system, named Tet-on-LMP1 HNE2 by PCR-ELISA analysis and reporter gene assay. Blocking of LMP1 expression decreased telomerase activity and c-myc transactivation. Mutagenesis of Myc-responsive E-box elements in the minimal core of hTERT promoter could inhibit the hTERT expression induced by LMP1. Moreover, blocking of c-myc transactivation could further decrease LMP1-mediated hTERT expression. It has been suggested that LMP1 can be used to aid myc control telomerase. In addition, we also found that C-terminus of LMP1, including CTAR1 and CTAR2 domains participated in telomerase activation. Together, these findings suggested that LMP1 activated telomerase via c-myc.

Blotting, Western↗
PubMed2003

Density fingering of an exothermic autocatalytic reaction.

Density fingering of exothermic autocatalytic fronts in vertically oriented porous media and Hele-Shaw cells is studied theoretically for chemical reactions where the solutal and thermal contribution to density changes have opposite signs. The competition between these two effects leads to thermal plumes for ascending fronts. The descending fronts behave strikingly differently as they can feature, for some values of the parameters, fingers of constant amplitude and wavelength. The differences between up and down going fronts are discussed in terms of dispersion curves and nonlinear dynamics. The theoretically predicted dispersion curves are experimentally evidenced with the chlorite-tetrathionate reaction.

Journal Article↗
PubMed2003

Biomechanical and morphometric intestinal remodelling during experimental diabetes in rats.

AIMS/HYPOTHESIS: Morphometric and passive biomechanical properties were studied in the duodenum, jejunum and ileum in 10 non-diabetic and 40 streptozotocin-induced diabetic rats. METHODS: The diabetic rats were divided into groups living 4 days, 1, 2, and 4 weeks after diabetes was induced ( n=10 for each groups). The mechanical test was done as a ramp distension experiment. The intestinal diameter and length were obtained from digitised images of the intestinal segments at pre-selected pressures and at no-load and zero-stress states. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter and pressure data and from the zero-stress state geometry. RESULTS: The blood glucose concentration increased four- to fivefold in the diabetic rats. Streptozotocin-induced diabetes generated pronounced increase in the weight per centimetre length, wall thickness and wall cross-sectional area in all intestinal segments during diabetes ( p<0.05). Histological analysis showed that the thickness of the intestinal layers was increased in all segments during diabetes ( p<0.05). In the duodenum the opening angle did not change in the first 2 weeks and decreased after 4 weeks ( p<0.05). In the jejunum and ileum the opening angle increased after 1 week in the diabetic group. The residual strain showed the same pattern as the opening angle. Furthermore, it was found that the circumferential and longitudinal stiffness of the intestinal wall increased with the duration of diabetes ( p<0.05 and p<0.01). CONCLUSION/INTERPRETATION: Morphological and biomechanical remodelling of the small intestine occurred during the development of diabetes.

Animals↗
PubMed2003

Epithelial cell-derived neutrophil-activating peptide-78 is present in fetal membranes and amniotic fluid at increased concentrations with intra-amniotic infection and preterm delivery.

Intra-amniotic secretion and abundance of epithelial cell-derived neutrophil-activating peptide (ENA)-78, a potent chemoattractant and activator of neutrophils, was studied in the context of term and preterm parturition. Staining of ENA-78 immunoperoxidase was localized predominantly to chorionic trophoblasts and amniotic epithelium in term and preterm gestational membranes, with weaker and less consistent staining in decidual cells. The abundance of ENA-78 in membrane tissue homogenates was significantly increased ( approximately 4-fold) with term labor in amnion (n = 15), and with preterm labor ( approximately 30-fold) in amnion and choriodecidua (n = 31). In amnion tissue homogenate extracts, ENA-78 levels were positively correlated with the degree of leukocyte infiltration (r2 = 0.481). In amniotic fluids, median ENA-78 levels from pregnancies with preterm labor without intra-amniotic infection were significantly lower (P < 0.01 by ANOVA) than those from pregnancies with preterm deliveries with infection; levels in samples derived from term pregnancies were similar before and after labor. Production of ENA-78 by amnion monolayers was stimulated in a concentration-dependent fashion by both interleukin-1beta and tumor necrosis factor alpha. Production of ENA-78 by choriodecidual explants was increased modestly after 2-4 h of exposure to lipopolysaccharide (5 microg/ml). An immunoreactive doublet ( approximately 8 kDa) was detected in choriodecidual explant-conditioned media by immunoblotting. We conclude that ENA-78, derived from the gestational membranes, is present in increased abundance in the amniotic cavity in response to intrauterine infection and, hence, may play a role in the mechanism of infection-driven preterm birth and rupture of membranes secondary to leukocyte recruitment and activation.

Amniotic Fluid↗