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Biomedical subjects

N Wei

Publications and source records attributed to N Wei.

At least 37 records · Page 2Linked to original sources
PubMed1999

Characterization of a magnetic bearing system and fluid properties for a continuous flow ventricular assist device.

This article presents the performance test results of the CFVAD3 continuous flow blood pump in an artificial human circulation system. The CFVAD3 utilizes magnetic bearings that support a thin pancake impeller, the shape of which allows for a very compact pump whose total axial length is less than 5 cm with a radial length of about 10 cm. This gives a total volume of about 275 cc. The impeller itself has 4 vanes with a designed operating point of 6 L/min at 100 mm Hg of differential pressure and 2,000 rpm. The advantages of magnetic bearings, such as large clearance spaces and no mechanical wear, are elaborated upon. Furthermore, bearing model parameters such as load capacity and current gains are described. These parameters in conjunction with the operating conditions during testing are then used to estimate the fluid forces, stiffness, and damping properties while pumping. Knowledge of these parameters is desirable because of their effects on pump behavior. In addition, a better plant model will allow more robust control algorithms to be devised that can boost pump performance and reliability.

Equipment Design↗
PubMed1999

Arabidopsis cop8 and fus4 mutations define the same gene that encodes subunit 4 of the COP9 signalosome.

The pleiotropic constitutive photomorphogenic/deetiolated/fusca (cop/det/fus) mutants of Arabidopsis exhibit features of light-grown seedlings when grown in the dark. Cloning and biochemical analysis of COP9 have revealed that it is a component of a multiprotein complex, the COP9 signalosome (previously known as the COP9 complex). Here, we compare the immunoaffinity and the biochemical purification of the COP9 signalosome from cauliflower and confirm its eight-subunit composition. Molecular cloning of subunit 4 of the complex revealed that it is a proteasome-COP9 complex-eIF3 domain protein encoded by a gene that maps to chromosome 5, near the chromosomal location of the cop8 and fus4 mutations. Genetic complementation tests showed that the cop8 and fus4 mutations define the same locus, now designated as COP8. Molecular analysis of the subunit 4-encoding gene in both cop8 and fus4 mutants identified specific molecular lesions, and overexpression of the subunit 4 cDNA in a cop8 mutant background resulted in complete rescue of the mutant phenotype. Thus, we conclude that COP8 encodes subunit 4 of the COP9 signalosome. Examination of possible molecular interactions by using the yeast two-hybrid assay indicated that COP8 is capable of strong self-association as well as interaction with COP9, FUS6/COP11, FUS5, and Arabidopsis JAB1 homolog 1, the latter four proteins being previously defined subunits of the Arabidopsis COP9 signalosome. A comparative sequence analysis indicated that COP8 is highly conserved among multicellular eukaryotes and is also similar to a subunit of the 19S regulatory particle of the 26S proteasome.

Alleles↗
PubMed1999

Holistic approach to health education on AIDS.

OBJECTIVE: To identify a method for health education using the example of an educational seminar on AIDS prevention and control at Hebei Medical University in China, 1994. METHODS: Our goal is the theoretical formulation of a unified community approach for problem solving through the combination of the self regulative approach and the case analytical approach. "Quality improvement", "essential quality" and "human ecosystems" provide the basic ideas for better understanding the integration of culture, science and technology within the "cultural norm". RESULTS: The present seminar was successfully organized for Chinese medical students based on the theme of "living with AIDS". Through this program, we identified that self regulative and case analytical approach were major issues for holistic approach to health education. We also identified that a community approach provides the scientific basis for health education in the community. CONCLUSIONS: The present paper generates a healthcare paradigm for surveillance in health/medical education. Through a better understanding of community approach, we related "community care" (emphasizing self, mutual, professional and institutional care) to the "practical norm"; and "preventive epidemiology" (emphasizing the unification of quality and quantity, as well as systems and population) to the "research norm".

Acquired Immunodeficiency Syndrome↗
PubMed1998

Reasons for non-compliance in colorectal cancer screening with fecal occult blood test.

OBJECTIVES: To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer. DESIGN AND SETTING: The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects. MAIN RESULTS: A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79. CONCLUSIONS: These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood.

Adult↗
PubMed1998

Screen compliance rates in 14-years annual screening program for colorectal cancer with immunochemical fecal occult blood test-- identification of higher priority subjects in health education.

OBJECTIVES: The present study was carried out to assess compliance rates with annual colorectal cancer screening for fecal occult blood, and to identify the subjects with higher priority in health education to increase screen compliance. DESIGN AND SETTING: A screening program for colorectal cancer was conducted between 1982 and 1995 in a Japanese villlage. Screen compliance rates in this program were summarised related to sex distribution as well as 10-year age cohorts. MAIN RESULTS: Screen compliance declined slowly during 14 years time period, and averaged 55.4%. Mean screen compliance was significantly higher in women (56.8%) than in men (53. 8%), and also in aged 50-79 (63.5%) than in aged 50 or less (43.8%), and those 80 and older(12.3%). Subjects who experienced a negative result on colonoscopic examination had significantly lower compliance with screening. CONCLUSIONS: These findings indicate that the youngest as well as oldest subjects, and the subjects with negative results of fecal occult blood test should be given higher priority in health education to improve screen compliance.

Aged↗
PubMed1998

Molecular interaction between COP1 and HY5 defines a regulatory switch for light control of Arabidopsis development.

Arabidopsis COP1 acts as a light-inactivable repressor of photomorphogenic development, but its molecular mode of action remains unclear. Here, we show that COP1 negatively regulates HY5, a bZIP protein and a positive regulator of photomorphogenic development. Both in vitro and in vivo assays indicate that COP1 interacts directly and specifically with HY5. The hyperphotomorphogenic phenotype caused by the over-expression of a mutant HY5, which lacks the COP1-interactive domain, supports the regulatory role of HY5-COP1 interaction. Further, HY5 is capable of directly interacting with the CHS1 minimal promoter and is essential for its light activation. We propose that the direct interaction with and regulation of transcription factors by COP1 may represent the molecular mechanism for its control of gene expression and photomorphogenic development.

Acyltransferases↗
PubMed1998

Combinatorial interaction of light-responsive elements plays a critical role in determining the response characteristics of light-regulated promoters in Arabidopsis.

We have studied the roles of PhyA, PhyB and CRY1 photoreceptors and the downstream light-signaling components, COP1 and DET1, in mediating high-irradiance light-controlled activity of promoters containing synthetic light-responsive elements (LRE). Promoters with paired LREs were able to respond to a wide spectrum of light through multiple photoreceptors, while the light-inducible single LRE promoters primarily responded to a specific wavelength of light. In addition, our results indicate that Cry1 is involved in PhyB-mediated red-light induction of the G-GATA/NOS101 promoter, and that both Cry1 and PhyB are required for effective repression of the GT1/NOS101 promoter by red or blue light. An interaction between PhyA and PhyB in mediating GT1-GATA/NOS101 promoter light activation was also observed. Furthermore, our data indicate that COP1 and DET1 exert negative control in the dark only on paired LRE promoters but not single LRE promoters. From these results, we conclude that the combinatorial interaction of LREs is essential in determining the ability of light-responsive promoters to be modulated by crucial cellular regulators and to respond to diverse light environments.

Arabidopsis↗
PubMed1998

Arabidopsis bZIP protein HY5 directly interacts with light-responsive promoters in mediating light control of gene expression.

The Arabidopsis HY5 gene has been defined genetically as a positive regulator of photomorphogenesis and recently has been shown to encode a basic leucine zipper type of transcription factor. Here, we report that HY5 is constitutively nuclear localized and is involved in light regulation of transcriptional activity of the promoters containing the G-box, a well-characterized light-responsive element (LRE). In vitro DNA binding studies suggested that HY5 can bind specifically to the G-box DNA sequences but not to any of the other LREs present in the light-responsive promoters examined. High-irradiance light activation of two synthetic promoters containing either the consensus G-box alone or the G-box combined with the GATA motif (another LRE) and the native Arabidopsis ribulose bisphosphate carboxylase small subunit gene RBCS-1A promoter, which has an essential copy of the G-box, was significantly compromised in the hy5 mutant. The hy5 mutation's effect on the high-irradiance light activation of gene expression was observed in both photosynthetic and nonphotosynthetic tissues. Furthermore, the characteristic phytochrome-mediated red light- and far-red light-reversible low-fluence induction of the G-box-containing promoters was diminished specifically in hy5 plants. These results suggest that HY5 may interact directly with the G-box in the promoters of light-inducible genes to mediate light-controlled transcriptional activity.

Arabidopsis↗
PubMed1998

S100+ cell response to squamous cell carcinoma of the lip: inverse correlation with metastasis.

Previous work has suggested a key role of dendritic cells in antineoplastic immunity. The course of mycosis fungoides and cancers of the lung, colon, thyroid and stomach has been associated with dendritic cell response to the primary tumor. However, this has not been reported for cutaneous or mucosal squamous cell carcinoma (SCC). Thirty-six cases of primary SCC of the lip mucosa or vermillion border, including nine cases with regional metastasis, were studied to investigate the relationship of dendritic cell density with age, tumor grade, mitotic rate, diameter, ulceration, depth of invasion, muscle invasion, tumor-infiltrating lymphocytes (TILs) and metastasis. Dendritic cells were identified using S100 immunohistochemistry, and their peritumor and intratumor density (peri-S100D and intra-S100D) were determined. The mean peri-S100D was 314 +/- 50/mm2. High peri-S100D was associated with lower rate of metastasis (P = 0.03), and no case with peri-S100D > 311/mm2 metastasized. Peri-S100D inversely correlated with depth of invasion (P = 0.04) and ulceration (P = 0.02), and positively associated with TILs (P = 0.02). The mean intra-S100D was 317 +/- 42/mm2. Intra-S100D did not quantitatively correlate with metastasis; however, no metastasis occurred when intra-S100D exceeded 515/mm2. Intra-S100D correlated with brisk TILs (P = 0.04). These results suggest a functional role of dendritic cells in the immune response to SCC. Peri-S100D may be a prognostic indicator.

Antigens, CD↗
PubMed1998

Characterization and purification of the mammalian COP9 complex, a conserved nuclear regulator initially identified as a repressor of photomorphogenesis in higher plants.

The COP9 complex has been identified as a repressor of photomorphogenesis in Arabidopsis. Here we demonstrate that the COP9 complex is also present in mammals. Specific antibodies were generated against human counterparts of the Arabidopsis COP9 and COP11, the two known subunits of plant COP9 complex. Using these antibodies, we showed that indeed mammalian COP9 and COP11, also known as GPS1, could be coimmuno-precipitated using either of the two specific antibodies, definitively confirming that they are physically part of the same complex. Further, the mammalian COP9 and COP11/GPS1 were cofractionated in the same large molecular weight fractions of about 500 kDa and were absent from the monomeric fractions. The mammalian COP9 complex was present in all organs examined but abundances vary. Indirect immunofluorescence studies suggested that the mammalian COP9 complex is largely nuclear localized. Both conventional biochemical and affinity purifications of the COP9 complex from pig spleen indicated that the mammalian COP9 complex consists of eight distinct subunits. These findings indicate that mammals also have a COP9 complex with conserved molecular composition and biochemical and cellular properties similar to the higher plant counterpart.

Animals↗
PubMed1997

Expression of vascular endothelial growth factor in synovial fibroblasts is induced by hypoxia and interleukin 1beta.

OBJECTIVE: To study the mechanism by which hypoxia and inflammatory cytokines mediate angiogenesis in the rheumatoid pannus through their effects on the fibroblast-like type B synoviocyte, the major cell type of normal synovia. METHODS: Fibroblasts were prepared from synovial tissue of healthy and diseased individuals, and cultured in the presence of various stimuli. The expression of vascular endothelial growth factor (VEGF) was assessed by ELISA and reverse transcription polymerase chain reaction. RESULTS: Unlike normal fibroblasts, synovial fibroblasts from rheumatoid arthritis (RA) and osteoarthritis constitutively secreted significant levels of VEGF, which is known to act directly on endothelial cells. VEGF secretion was further inducible by both hypoxia and interleukin 1beta (IL-1beta) and these increases were additive. In contrast, tumor necrosis factor alpha was unable to induce VEGF expression. CONCLUSION: Under hypoxia or IL-1 stimulation, conditions common to the inflamed synovium, type B synoviocytes secrete increased levels of VEGF, which is likely to act on nearby endothelia, promoting angiogenesis. The constitutive expression of VEGF in rheumatoid synovial fibroblasts may reflect an altered phenotype involved in the pathology of RA.

Alternative Splicing↗
PubMed1997

The holmium YAG laser in office based arthroscopy of the knee: comparison with standard interventional instruments in patients with arthritis.

OBJECTIVE: To confirm the feasibility of laser assisted technology in an office based rheumatology practice and to compare selected outcome variables with those of conventional arthroscopic cutting tools. METHODS: A prospective analysis of 70 office based arthroscopies on 70 patients with knee arthritis over an 8 month period. All patients met specific criteria for office based arthroscopy. Thirty-six patients had interventions with conventional cutting tools and 34 patients had interventions with a 40 watt holmium YAG laser. Variables assessed included procedure time, length of recuperative period, and postprocedural pain. RESULTS: Laser assisted arthroscopy was performed in 34 cases without side effects or complications. Patients who received laser treatment had a shorter recuperative period, less postprocedural pain, and fewer hemarthroses than patients treated with conventional methods. CONCLUSION: While recognizing the shortcomings and possible complications associated with laser surgery, we conclude that laser use in an office setting is not only feasible but may in the future be an excellent method for office based arthroscopic treatment of the arthritic knee.

Adult↗
PubMed1997

A unique intronic splicing enhancer controls the inclusion of the agrin Y exon.

Alternative splicing of the agrin mRNA controls the ability of agrin protein to induce the clustering of acetylcholine receptors at the neuromuscular junction. Using a transfectable reporter gene, we show that one agrin alternative exon, the Y exon, is controlled by a regulatory sequence in the downstream intron. Portions of this intronic sequence have the properties of a splicing enhancer that can activate splicing of a heterologous exon when placed in the intron downstream. The regulatory region is complex in structure, containing several different elements capable of activating splicing. Individual enhancing elements differ in their cell-type specificity, and are not apparently synergistic, as two elements together induce lower splicing than either does separately. Essential nucleotides within these regulatory elements were identified by scanning mutagenesis across the active region. Interestingly, the elements do not appear similar to known intronic splicing enhancer elements. This Y exon enhancer and its components take part in an apparent combinatorial system of control where multiple regulatory elements of varying activity combine to produce a precisely cell-specific exon inclusion. As a major contributor to the regulation of the Y exon, the enhancer ultimately controls the properties of the agrin protein.

3T3 Cells↗
PubMed1996

Combinatorial interplay of promoter elements constitutes the minimal determinants for light and developmental control of gene expression in Arabidopsis.

Higher plants are able to integrate environmental and endogenous signals to regulate gene expression for optimal development. To define the minimal sequence requirement sufficient to integrate light and developmental signals in controlling promoter activity, we carried out a systematic analysis of the roles of four well-conserved 'light-responsive elements (LREs)' common to many nuclear-encoded photosynthetic genes. A gain-of-function assay using basal promoter-reporter fusions in stable transgenic Arabidopsis was employed to demonstrate that pairwise combinations of the LREs, but not the individual elements alone, can confer light-inducible expression to the reporter gene independently of the basal promoter context and the light-triggered morphological changes. The activity of the synthetic promoters with the paired LREs can be modulated at least by the phytochrome system. Further, those synthetic light-regulated promoters confer a photosynthetic cell-specific expression pattern and respond to the chloroplast development state. Our data suggest that distinct combinatorial interactions of LREs can serve as minimal autonomous promoter determinants which integrate light and developmental signals and modulate promoter activity.

Arabidopsis↗
PubMed1996

The COP9 complex, a novel multisubunit nuclear regulator involved in light control of a plant developmental switch.

Arabidopsis COP9 is a component of a large protein complex that is essential for the light control of a developmental switch and whose conformation or size is modulated by light. The complex is acidic, binds heparin, and is localized within the nucleus. Biochemical purification of the complex to near homogeneity revealed that it contains 12 distinct subunits. One of the other subunits is COP11, mutations in which result in a phenotype identical to cop9 mutants. The COP9 complex may act to regulate the nuclear abundance of COP1, an established repressor of photomorphogenic development. During the biogenesis of the COP9 complex, a certain degree of prior subunit association is a prerequisite for proper nuclear translocation. Since both COP9 and COP11 have closely related human counterparts, the COP9 complex probably represents a conserved developmental regulator in higher eukaryotes.

Arabidopsis↗
PubMed1996

Evidence for FUS6 as a component of the nuclear-localized COP9 complex in Arabidopsis.

The pleiotropic CONSTITUTIVE PHOTOMORPHOGENIC (COP), DEETIOLATED (DET), and FUSCA (FUS) loci are essential regulatory genes involved in the light control of seedling developmental patterns in Arabidopsis. Although COP1, DET1, COP9, and FUS6 (also called COP11) have been cloned, their biochemical activities and interactions remain elusive. We have recently suggested that multiple pleiotropic COP, DET, and FUS genes may encode subunits of a large regulatory complex. In this study, we generated specific antibodies against Arabidopsis FUS6 and show that accumulation of both COP9 and FUS6 is coordinated in the pleiotropic cop, det, and fus mutant backgrounds and in wild-type plants throughout development. Both COP9 and FUS6 cofractionated into identical high molecular mass fractions in an analytical gel filtration assay, and neither was found in its monomeric form. Moreover, antibodies raised against either COP9 or FUS6 selectively coimmunoprecipitated both proteins. We have also developed an Arabidopsis protoplast immunolocalization assay and demonstrated that the COP9 complex is localized in the nucleus and that its nuclear localization is not affected by light conditions or tissue types. The integrated genetic and biochemical results strongly support the conclusion that both COP9 and FUS6 are components of the nuclear-localized COP9 complex. Therefore, we have provided the strongest evidence for the conclusion that at least some of the pleiotropic COP, DET, and FUS loci act in the same signaling pathway.

Arabidopsis↗
PubMed1995

Immunodetection, expression strategy and complementation of turnip crinkle virus p28 and p88 replication components.

The plus-sense RNA genome of turnip crinkle virus (TCV) encodes at its 5' end a 28-kDa protein of unspecified function. Readthrough suppression of the p28 stop codon allows for the production of an 88-kDa product which is required for genome replication. Immunological analysis of the expression of p28 and p88 demonstrated that: (i) the genome directs the synthesis of polypeptides of approximately 28 and 88 kDa, (ii) the 88-kDa protein is immunologically related to p28, consistent with p88 being a readthrough product, and (iii) p28, but not p88, is detectable in vivo. An in vivo assay, in which readthrough is linked to the expression of a beta-glucuronidase reporter gene, showed that readthrough of the p28 amber stop codon occurs with an efficiency of approximately 1%. A similar efficiency of readthrough was observed when an altered context from the nonviable TCV mutant, mA2, containing a disrupted secondary structure (FfFa) spanning the p28 termination codon, was tested. This result suggests that the defective phenotype of mA2 is likely not linked to an alteration in readthrough efficiency. Additional studies demonstrated that complementation occurs in coinoculations with two nonviable TCV mutants, RT and APA, which are unable to express either p28 or p88, respectively. This result verifies that p28 is essential for TCV genome replication and provides the first definitive evidence for the role of a 5'-proximal open reading frame for any member of the family Tombusviridae.

Base Sequence↗