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R Wei

Publications and source records attributed to R Wei.

At least 19 recordsLinked to original sources
PubMed2006

Structural characterization of enterobactin hydrolase IroE.

The proliferation of many pathogenic bacteria is limited by the scarcity of soluble iron in their environment. Many of these bacteria scavenge iron by synthesizing and exporting small molecule siderophores that chelate iron. Iron-bound siderophores are subsequently imported for metabolic processing. Three related serine hydrolases have been characterized biochemically in this pathway: Fes, IroD, and IroE. Here, we report the crystal structure of IroE from uropathogenic Escherichia coli CFT073. The native structure and a complex with diisopropyl fluorophosphonate (DFP, a potent serine hydrolase inhibitor) were determined at 2.3 and 1.4 A resolution, respectively. IroE has the typical alpha/beta-hydrolase fold with an atypical catalytic dyad composed of Ser 189 and His 287. Mutation of either residue was detrimental to catalysis. In addition, rather than the typical oxyanion hole composed of backbone amides, IroE employs the atypical guanidinium moiety of Arg 130. Asp 90 anchors Arg 130 in the active site, and mutation of either residue was likewise detrimental to catalysis. We also compare the structure of IroE to the structure of Fes from Shigella flexneri (PDB entry 2B20). Both enzymes have similar active sites, but Fes has an additional amino-terminal lid domain. These lid domains are proposed to confer specificity to these related hydrolases.

Amino Acid Substitution↗
PubMed2006

Essential role of Ca2+ release channels in angiotensin II-induced Ca2+ oscillations and mesangial cell contraction.

The increased resistance of the glomerulus as a result of contractile dysfunction of mesangial cells (MCs) is associated with reduction of glomerular filtration rate and development of glomerulosclerosis. Evidences show MCs contraction changes with intracellular Ca(2+) concentration ([Ca(2+)](i)). Here, we explore the mechanism of angiotensin II (AngII)-induced Ca(2+) oscillations and MCs contraction. Primary MCs from 3-month-old and 28-month-old rats were used for detection of Ca(2+) oscillations and MC planar area with confocal microscopy. AngII could induce typical Ca(2+) oscillations and contraction of MCs. This process was abolished by thapsigargin, 2-aminoethoxydiphenyl borate, or 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine, and partially inhibited by ryanodine, but could not be inhibited in the absence of extracellular Ca(2+). Ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate (InsP(3)) receptors displayed a strong colocalization, which may contribute to the amplification of Ca(2+) response. MLC(20) phosphorylation and MC planar area were associated with AngII-induced Ca(2+) oscillations. The frequency of Ca(2+) oscillations was dependent on the AngII concentration and correlated with the MCs' contractive extent, which could be attenuated by KN-93. The amplitude reduction of oscillations correlated with the decrease in aging-related contraction. In conclusion, [Ca(2+)](i) response of MCs to AngII is characterized by repetitive spikes through the following repetitive cycles: Ca(2+) release by phospholipase C -InsP(3) pathway, Ca(2+) amplification by Ca(2+)-activated RyRs and Ca(2+) reuptake by the endoplasmic reticulum. MCs contraction can be modulated by oscillations not only in an AngII-induced frequency-dependent mode but also in an aging-related, amplitude-dependent mode.

Angiotensin II↗
PubMed2006

Chlamydia psittaci is variably associated with ocular adnexal MALT lymphoma in different geographical regions.

Infectious agents play a critical role in MALT lymphoma development. Studies from Italy showed Chlamydia psittaci infection in 87% of ocular adnexal MALT lymphomas and complete or partial regression of the lymphoma after C. psittaci eradication in four of nine cases. However, C. psittaci was not demonstrated in ocular adnexal MALT lymphomas from the USA. This study was thus designed to investigate further the role of C. psittaci, and other infectious agents commonly associated with chronic eye disease, in the development of ocular adnexal MALT lymphoma. The presence of C. psittaci, C. trachomatis, C. pneumoniae, herpes simplex virus 1 and 2 (HSV1, HSV2), and adenovirus 8 and 19 (ADV8, ADV19) was assessed separately by polymerase chain reaction in 142 ocular adnexal MALT lymphomas, 53 non-marginal zone lymphomas, and 51 ocular adnexal biopsies without a lymphoproliferative disorder (LPD), from six geographical regions. C. psittaci was detected at similar low frequencies in non-LPD and non-marginal zone lymphoma groups from different geographical regions (0-14%). Overall, the prevalence of C. psittaci was significantly higher in MALT lymphomas (22%) than in non-LPD (10%, p=0.042) and non-marginal zone lymphoma cases (9%, p=0.033). However, the prevalence of C. psittaci infection in MALT lymphoma showed marked variation among the six geographical regions examined, being most frequent in Germany (47%), followed by the East Coast of the USA (35%) and the Netherlands (29%), but relatively low in Italy (13%), the UK (12%), and Southern China (11%). No significant differences in the detection of C. pneumoniae, C. trachomatis, HSV1, HSV2, ADV8, and ADV19 were found between lymphomas and controls from different geographical regions. In conclusion, our results show that C. psittaci, but not C. pneumoniae, C. trachomatis, HSV1, HSV2, ADV8 or ADV19, is associated with ocular adnexal MALT lymphoma and that this association is variable in different geographical areas.

Adenoviridae↗
PubMed2003

HIV insertions within and proximal to host cell genes are a common finding in tissues containing high levels of HIV DNA and macrophage-associated p24 antigen expression.

HIV integration within host cell genomic DNA is a requisite step of the viral infection cycle. Yet, characteristics of the sites of provirus integration within the host genome remain obscure. The authors present evidence that in diseased tissues showing a high level of HIV DNA and macrophage-associated HIV p24 antigen expression from end stage forms of HIV disease, HIV-1 integration sites were favored within genes and transcriptionally active host cell genomic loci. Using an inverse PCR (IPCR) technique that identified dominant integrated forms of HIV, clonal IPCR products were isolated from AIDS dementia, AIDS lymphoma, and angioimmunoblastic lymphadenopathy tissues. Thirty of 34 disease-associated HIV-1 insertions were identified within annotated and hypothetical genes, an unexpected but highly nonrandom genetic coding region association (p <.026). The 1% sensitivity thresholds used for HIV IPCR suggested some form of selective expansion of cells containing these HIV proviruses. Consistent with this interpretation were the HIV-1 insertion sites identified within introns of genes that encoded for factors associated with signal transduction, apoptosis, and transcription regulation. In addition, HIV-1 proviruses were frequently found proximal to genes that encoded for receptor-associated, signal transduction-associated, transcription-associated, and translation-associated proteins. HIV-1 integration within host cell genomic DNA potentially represents a significant insertional mutagenic event. In certain cases, provirus insertions may mediate the dysregulation of specific gene expression events, providing mechanisms contributing to the pathogenesis associated with certain AIDS-related diseases.

Chromosomes, Human↗
PubMed2003

An evaluation of the NRC (1998) growth model in estimating lysine requirements of barrows with a lean growth rate of 348 g/d.

Two experiments were conducted to evaluate the NRC (1998) growth model in predicting lysine requirements of high lean gain barrows by using plasma urea nitrogen as a rapid response criterion. In Exp. 1, 20 PIC barrows with an initial BW of 19.1 kg were used to estimate total lysine requirements at approximately 30 and 50 kg of BW in two separate randomized complete block designs. Another set of 20 PIC barrows with an initial BW of 59.0 kg was used to estimate total lysine requirements at about 70, 90, and 110 kg of BW in three separate, completely randomized designs. Pigs were individually penned and had free access to feed and water. Results indicated that total lysine requirements at 33, 52, 72, 93, and 113 kg of BW were 0.96 +/- 0.01, 0.85 +/- 0.02, 0.76 +/- 0.05, 0.66 +/- 0.03, and 0.49 +/- 0.21% of the diet (18.6 +/- 0.2, 20.1 +/- 0.5, 22.6 +/- 1.5, 18.7 +/- 0.8, and 16.8 +/- 7.2 g/d), respectively. The precision of the estimation decreased when pigs reached 70 kg of BW. To increase the precision, Exp. 2 was conducted in which 20 PIC barrows with an initial BW of 45.2 kg were repeatedly used in Latin square designs to estimate total as well as true ileal digestible lysine requirements at BW ranges of from 60 to 80, 80 to 100, and 100 to 120 kg, respectively. During the three BW range periods, the individually penned pigs were limited in feed intake to 2.6, 2.8, and 3.0 kg/d, respectively, and fed once daily. The estimated requirements in the three BW ranges were 21.8 +/- 0.5, 18.8 +/- 0.5, and 20.2 +/- 0.7 g/d in total lysine and 19.9 +/- 0.6, 17.0 +/- 0.5, and 18.1 +/- 0.6 g/d in true ileal digestible lysine, respectively. Total lysine requirements at approximately 30, 50, 70, 90, and 110 kg of BW were about 102, 98, 106, 92, and 99% of the NRC (1998) recommendations, respectively. The close agreement validated the NRC growth model in predicting lysine requirements of high lean gain barrows over the growing-finishing period.

Animals↗
PubMed2003

Analysis of factors influencing the blood levels and activities of tissue-type plasminogen activator (t-PA).

This study aimed to correlate plasmatic tissue-type plasminogen activator (t-PA) levels and activity with parameters of artery blood flow and vessel walls, nail fold microcirculation, hemorheology, serum glucose, and lipids. Thirty healthy volunteers (female/male 12/18) aged 40-60 (average 46) were included in the study. In citrate venous blood, the following parameters were determined: carotid mean velocity, carotid intimal-medial-thickness (IMT), capillary circulation parameters, hemorheology index, serum glucose, and lipids. Analysis of data showed that t-PA concentration was positively and significantly correlated with total cholesterol, triglycerides, and serum glucose (P<0.05, P<0.05, and P<0.01), but t-PA activity showed no correlation with them; among the hemorheology factors investigated, t-PA concentration showed the strongest positive correlation with both whole blood viscosity and reduced blood viscosity at high and low shear rate separately (P<0.01), t-PA activity showed no correlation with any hemorheology factors; t-PA concentration showed no correlation with any investigated nail fold capillary parameters, whereas t-PA activity was significantly and negatively associated with capillary loop number (P<0.05); t-PA concentration and activity was not associated with values of carotid maximum intimal-medial-thickness (mIMT) and mean velocity or systolic, diastolic blood pressure (P>0.05). But subjects with mIMT 1.0 mm showed higher t-PA levels compared with those with mIMT < 1.0 mm (P<0.05) and decreased carotid mean velocity (P<0.01). These findings suggest that multiple vascular disease risk factors would influence the t-PA level; t-PA concentration does not parallelize with t-PA activity.

Adult↗
PubMed2001

[Therapeutic effect of gamma-ray stereotactic radiotherapy on brain metastases].

OBJECTIVE: To evaluate the therapeutic effects of gamma-ray stereotactic radiotherapy (SRT) plus whole brain irradiation and radiotherapy alone in brain metastases. METHODS: Forty-three patients with brain metastases were treated by SRT plus whole brain irradiation and 50 patients were treated by routine radiotherapy. SRT was given with the dosage of 15-27 Gy, and whole brain irradiation was given with the dosage of 30-40 Gy. RESULTS: One-year survival rate, median survival period, and tumor local control rate in SRT plus whole brain irradiation group were higher or longer than those in the routine radiotherapy group (P < 0.01). Mortality in SRT plus whole brain irradiation group was lower than that in the routine radiotherapy group (P < 0.05). CONCLUSION: The therapeutic effect of SRT plus whole brain irradiation on brain metastasis of cancer is superior to the routine radiotherapy.

Adult↗
PubMed2001

Dissipative properties and scaling law for a layer of granular material on a vibrating plate.

The dissipative properties and scaling law for a layer of vertically vibrated granular materials were investigated by means of a dynamical model of a single sphere colliding completely inelastically with a massive, oscillating plate. A relationship is presented of how the temperature of the layer scales with the acceleration of the plate and the restitution coefficient of the grains. The numerical calculation shows the existence of an "energy well" and a "temperature well," which could be used to explain the existence of a f/2 flat (where f is the external driving frequency) state in an experiment on vibrated granular material.

Journal Article↗
PubMed2001

Cytotoxic effects of antiproliferative agents on human retinal glial cells in vitro.

PURPOSE: Proliferative vitreoretinopathy (PVR) is characterized by the formation of cellular membranes on the detached retina and also in the vitreous. Glial cells can be found in epiretinal and subretinal membranes from eyes with PVR, proliferative diabetic retinopathy (PDR), idiopathic macular pucker, uveitis and other diseases affecting the retina. Proliferation and contraction of glial cells appears to play a role in the pathogenesis of PVR. This study is designed to inspect the effectiveness of harringtonine, as well as colchicine, daunomycin and fluorouracil, against cellular proliferation of cultured human retinal glial cells that might be involved in the retinal and/or vitreous proliferation. METHODS: Cultures of human retinal glial cells were prepared using the enzyme digesting method. Cells that had been in culture for 2-5 passages were used in this study. Harringtonine (0.063 microg/ml approximately 2.0 microg/ml), colchicines (0.5 microg/ml approximately 16.0 microg/ml), daunomycin (0.1 microg/ml approximately 3.2 microg/ml) and 5-fluorouracil (0.5 microg/ml approximately 16.0 microg/ml) were added to cultures of human retinal glial cells and the proliferation rates of the cells were measured by the MTT method. RESULTS: Harringtonine at the dosage of 0.063 microg/ml induced suppression of cellular growth, but the changes were not statistically significant (p > 0.05). At a dosage ranging from 0.125 microg/ml to 2.0 microg/ml, harringtonine significantly suppressed cellular growth according to the test (p < 0.01). Likewise, other antiproliferative agents inhibited cellular growth significantly at a dosage from 1.0 microg/ml to 16.0 microg/ml (colchicine), 0.2 microg/ml to 3.2 microg/ml (daunomycin) and 1.0 microg/ml to 16.0 microg/ml (5-fluorouracil), but not at 0.5 microg/ml (colchicine), 0.1 microg/ml (daunomycin) and 0.5 microg/ml (5-fluorouracil). The ID50 were 0.33 microg/ml (harringtonine), 3.11 microg/ml (colchicine), 0.79 microg/ml (daunomycin) and 5.23 microg/ml (5-fluorouracil), respectively. CONCLUSIONS: Harringtonine was extremely effective in inhibiting human retinal glial cell proliferation, like other antiproliferative drugs such as colchicine, daunomycin and 5-fluorouracil. Harringtonine, therefore, may be a candidate for further studies regarding the treatment of experimental PVR.

Adult↗
PubMed2001

Prevalence of overweight in US children: comparison of US growth charts from the Centers for Disease Control and Prevention with other reference values for body mass index.

BACKGROUND: Several different sets of reference body mass index (BMI) values are available to define overweight in children. OBJECTIVE: The objective of this study was to compare the prevalence of overweight in US children calculated with 3 sets of reference BMI values: the revised growth charts of the Centers for Disease Control and Prevention (CDC-US growth charts), international standards proposed by Cole et al, and values developed by Must et al. DESIGN: Data for children and adolescents came from cross-sectional nationally representative US surveys: cycles II and III of the National Health Examination Survey (1963-1965 and 1966-1970) and the first, second, and third National Health and Nutrition Examination Surveys: NHANES I (1971-1974), II (1976-1980), and III (1988-1994). The reference values of Cole et al equivalent to a BMI of 25 were compared with the 85th percentiles from the other 2 methods; the values equivalent to a BMI of 30 were compared with the 95th percentiles. RESULTS: The 3 methods gave similar but not identical results. The reference values of Cole et al gave lower estimates than did the CDC-US growth charts for young children but higher estimates for older children. The reference values of Must et al gave much higher prevalences for younger girls than did the other 2 methods. CONCLUSIONS: Differences between methods were related to differences in data sets, smoothing methods, and theoretical approaches. All 3 methods are based on statistical criteria and incorporate arbitrary assumptions. These methods should be used cautiously, with awareness of the possible limitations.

Adolescent↗
PubMed2001

[Removing the nitrogen from the ammonium sulfite method paper mill wastewater by anoxic/aerobic SBR].

The experiment results showed that the best technology of removing the nitrogen was anoxic time to aerobic time of 1:1.5, a cycle of 8 hours; the SRT should be more than 12 d and the loading of NH3-N should be less than 0.063 g/(g.d); when the concentration of CODCr, NH3-N and NOx-N was 1200-1800 mg/L, 135-200 mg/L and 7-10 mg/L respectively, without external carbon sources, the removal rate of NH3-N and TN could respectively achieve 95% and 66%; after adding sodium acetate the removal rate of TN could get to 85%. The addition of sodium acetate at the concentration equivalent to theoretical CODCr values of 125 mg/L appeared to be the most economical and reliable option.

Aerobiosis↗
PubMed2000

CDC growth charts: United States.

OBJECTIVES: This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts. METHODS: Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves. RESULTS: The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast- and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years. CONCLUSION: Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.

Adolescent↗
PubMed2000

Cellular consequences in the brain and liver of age-specific selection for rate of development in mice.

Changes in cell number (hyperplasia) and cell size (hypertrophy) in the brain and liver are described for mice subjected to 24 generations of age-specific restricted index selection for rate of development in body weight. One selection treatment (E) altered rate of development between birth and 10 days of age, another treatment (L) involved changes in rate of development between 28 and 56 days of age, while a third control treatment (C) involved random selection. Each selection treatment was replicated three times. These age-specific selection treatments focused on intervals during ontogeny when different developmental processes (hypertrophy or hyperplasia) were more predominant in the control of growth. Significant changes in brain and liver weight occurred at both 28 and 70 days of age. Early selection (E) generated significant changes in the number of cells in the brain while later selection (L) had no effect since the brain had stopped growth before selection was initiated. For the liver, early and late selection produced significant effects on both cell number and cell size. These results describe the dynamic and multidimensional aspects of selection in terms of its ability to alter different cellular and developmental components of complex morphological traits.

Aging↗
PubMed2000

[The contribution of phacoemulsification to combined cataract and glaucoma surgery].

OBJECTIVE: To study the safety and effectiveness of phacoemulsification (phaco) in trabeculectomy combined with cataract extraction (phacotrabeculectomy) and posterior chamber intraocular lens (IOL) implantation. METHODS: 68 eyes with glaucoma and cataract were randomly divided into two groups: the phacotrabeculectomy with IOL implantation and modern extracapsular cataract extraction (ECCE), trabeculectomy and IOL implantation. RESULTS: Postoperatively, in the phaco group, the intraocular pressure (IOP) decreased obviously at the early stage (P < 0.05), the number of cases necessary for the use of anti-glaucoma drug was decreased, the mean kinds of the drug applied were markedly decreased (P < 0.05), the visual acuity improved quickly, significantly and steadily, and the complications were less than that in the ECCE group. CONCLUSIONS: The phaco's triple surgery is safe and effective. In cases with glaucoma and cataract, the surgery is indicated even when the cataract is not mature or premature.

Aged↗
PubMed1999

Neurotrophins and the anti-inflammatory agents interleukin-4 (IL-4), IL-10, IL-11 and transforming growth factor-beta1 (TGF-beta1) down-regulate T cell costimulatory molecules B7 and CD40 on cultured rat microglia.

Microglia are essential for T cell activation in the CNS. Since T cell activation requires costimulation by B7 and/or CD40, we examined the regulation by cytokines of B7-1, B7-2 and CD40 mRNA expression in cultured rat microglia in serum-free medium. All three ligands are expressed constitutively, but are profoundly up-regulated by granulocyte-macrophage colony-stimulating factor (GM-CSF). By contrast, interferon-gamma raises only B7-2 and CD40 mRNA, and the B7-2 increase is inhibited by IL-10. IL-4, transforming growth factor-beta1, and nerve growth factor (NGF) repress GM-CSF-induced B7-2 and CD40, but not B7-1. NGF also down-regulates its own high-affinity trkA receptor. IL-11, unrecognized for its effect on antigen presentation, represses GM-CSF-induced B7-2.

Animals↗
PubMed1999

[Analysis of MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos].

OBJECTIVE: To study the MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos. METHODS: MRI and CT scans of 51 patients were examined. RESULTS: MRI offers more information for evaluation of soft tissue lesions; the cavernous hemangioma and dermoid cyst were found to present rather characteristic images. Whereas in evaluation of lesions involving bony structures and calcifications, CT was superior to MRI. CONCLUSION: CT and MRI may evaluate the tumor location, extension into adjacent areas and are valuable in differential diagnosis of paranasal sinuses and orbitocranial disorder with secondary exophthalmos.

Adolescent↗