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Biomedical subjects

Y Wu

Publications and source records attributed to Y Wu.

At least 199 records · Page 11Linked to original sources
PubMed2001

Steroidal saponins from Tribulus terrestris.

Three new steroidal saponins were isolated from the fruits of Tribulus terrestris, and their structures were elucidated as (25R,S)-5 alpha-spirostane-12-one-3 beta-ol-3-O-beta-xylopyranosyl(1-->2)- [beta-xylopyranosyl(1-->3)]-beta-glucopyranosyl(1-->4)-[alpha-rhamno- pyranosyl(1-->2)]-beta-galactopyranoside; 26-O-beta-glucopyranosyl-(25S)-5 alpha-furostane-12-one-3 beta,22 alpha,26-triol-3-O-beta-glucopyranosyl(1-->2)-beta-galactopyranoside; 26-O-beta-glucopyranosyl-(25S)-5 alpha-furostane-12-one-3 beta,22 alpha,26-triol-3-O-beta-glucopyranosyl(1-->4)-[alpha- rhamnopyranosyl(1-->2)]-beta-galactopyranoside, respectively, by spectroscopic analysis and color reaction.

Carbohydrate Sequence↗
PubMed2001

Interpretation of nonfatal events after cardiac surgery: actual versus actuarial reporting.

OBJECTIVE: To describe the cumulative incidence (actual) method of analysis and to contrast it with the Kaplan-Meier method. METHOD: We use data on porcine valve replacement to illustrate these two statistical techniques. RESULTS: The "actual" analysis estimates the percentage of events expected to occur. The percentage given by the Kaplan-Meier method is much larger. CONCLUSION: Actual (cumulative incidence) analysis is preferred for estimating the probability of occurrence of a nonfatal time-related event.

Actuarial Analysis↗
PubMed2001

Cementless Lord total hip arthroplasty: cup loosening common after minimum 10-year follow-up of 103 hips.

We evaluated the clinical and radiographic results of 103 (88 patients) cementless Lord total hip arthroplasty after a mean follow-up period of 12.5 (10-16) years. 77 hips had arthrosis, 15 rheumatoid arthritis and 11 osteonecrosis. The preoperative mean Harris Hip Score improved from 47 (19-66) to 87 (62-99) at 5 years, but declined to 77 (56-97) at the final examination. The survivorship of the cup, using radiographically confirmed aseptic loosening as the end point, was 63% at 10 years and 45% at 15 years and the survivorship of the stem was 97% at 10 years and 96% at 15 years. The low figures of the cup may be due to insufficient contact between the smooth-surfaced threads of the cup and the acetabular bone. Thinner polyethylene, insufficient initial bone coverage, and larger femoral head diameter were significantly related to the occurrence of loosening. We can not recommend this smooth-surfaced threaded cup because of its high failure.

Adult↗
PubMed2001

Clinical definition of hereditary non-polyposis colorectal cancer: a search for the impossible?

Hereditary non-polyposis colorectal cancer is an autosomal dominant inherited disorder that predisposes its carriers to an almost 100% lifetime risk of cancer, in particular colorectal and endometrial cancer. Germline mutations, resulting in a deficient DNA mismatch repair system, are responsible for the disease. Because of the lack of specific phenotypical features, clinical diagnosis in an individual patient is impossible and relies heavily on family history. Genetic diagnosis by mismatch detection is now possible in a substantial proportion of families. Thus there is a great need for reliable but simple criteria that will help clinicians to recognize patients and families who can be referred for genetic diagnostics. In this article the different criteria that have been formulated and published in recent years are reviewed and the results, in terms of the proportions of subjects satisfying the criteria who were found to have a germline mutation, are discussed. In most studies the criteria were evaluated in only a small number of subjects. A population-based study is currently being carried out in the north of The Netherlands that aims to include 400 patients fulfilling one of a few simple criteria. Mutation analysis will be performed in all patients. The results of this study will help in the formulation of accurate and simple criteria for use in clinical practice.

Colorectal Neoplasms, Hereditary Nonpolyposis↗
PubMed2001

Source contributions to ambient concentrations of CO and NOX in the urban area of Beijing.

An emission inventory based on GIS technology was developed in this study, and used to estimate the spatial distribution of the stationary and mobile sources in the urban area of Beijing. The stationary sources were divided into various types of finer classes depending on different usage, stack height and emission factors. The mobile sources were treated as both line sources and area sources. It was shown that total anthropogenic CO and NOX emissions had reached 1.4 million and 233 thousand tons, respectively, and vehicle sources emissions of CO and NOX accounted for 76.8% and 40.2%, respectively, of the total emissions in 1995. ISCST3, a Gaussian dispersion air quality model, was modified at low wind speed condition, and then used to facilitate the study of source contributions to ambient concentrations of CO and NOX in Beijing. The simulation results showed that emissions from the vehicle sources had contributed 76.5% and 68.4% of the total CO and NOX concentrations in urban atmosphere of Beijing in 1995, and were even higher in the city core (86.3% of the CO and 72.0% of the NOX). Therefore, strategies for CO and NOX pollution control will of necessity need to focus on the vehicle sources.

Air Movements↗
PubMed2001

Impairment of mucosal immunity by parenteral nutrition: depressed nasotracheal influenza-specific secretory IgA levels and transport in parenterally fed mice.

OBJECTIVE: To examine the effects on mucosal selective transport of polymeric IgA (pIgA) and the ability of exogenous pIgA to provide protection despite altered mucosal transport. SUMMARY BACKGROUND DATA: Parenteral nutrition significantly impairs established antipseudomonal immunity and IgA-mediated antiviral immunity in association with gut-associated lymphoid tissue mass atrophy. Lack of enteral feeding also induces mucosal effects. METHODS: After immunization, nasotracheal levels of influenza-specific IgA were measured in cannulated mice randomized to chow feeding or parenteral nutrition. Nonimmune animals were randomized to chow or total parenteral nutrition, and after 5 days of diet were given a mixture of two antiinfluenza monoclonal antibodies, pIgA and IgG. Four hours after injection, nasal washes were collected and influenza-specific antibody levels were determined by enzyme-linked immunosorbent assay to calculate the selective transport index of IgA relative to IgG. In the final experiment, immunized animals were randomized to chow or parenteral feeding, and after 5 days, parenterally fed animals received either normal mouse serum or antiviral pIgA before viral challenge. Viral shedding was measured at 42 hours after challenge. RESULTS: Parenteral nutrition significantly reduced virus-specific IgA in nasotracheal washes. Parenteral nutrition depressed the selective transport index, demonstrating impaired mucosal transport of pIgA. Parenterally fed animals given specific antiviral pIgA but not normal mouse serum eliminated virus from the airway and regained mucosal protection, demonstrating adequate residual transport for immunity if adequate pIgA is present. CONCLUSION: Although both decreased IgA production due to gut-associated lymphoid tissue atrophy and impaired mucosal transport occur when enteral feeding is not provided, residual transport can provide antiviral protection if exogenous antiviral pIgA is available. Production, rather than transport, may be the most important factor in maintaining established respiratory tract IgA-mediated immunity.

Analysis of Variance↗
PubMed2001

Effect of recombinant bactericidal/permeability-increasing protein on endotoxin translocation and lipopolysaccharide-binding protein/CD14 expression in rats after thermal injury.

OBJECTIVE: To investigate the potential mechanisms underlying the in vivo effect of recombinant bactericidal/permeability-increasing protein (rBPI21) on endogenous bacteria or endotoxin translocation and lipopolysaccharide-binding protein/CD14 expression secondary to thermal injury. DESIGN: Prospective, randomized, controlled animal study. SETTING: College hospital animal research laboratory. SUBJECTS: Thirty-six male Wistar rats weighing 250-300 g. INTERVENTIONS: The rats were anesthetized, and a 35% total body surface area full-thickness burn was created. Animals were randomized to receive treatment with either rBPI21 or the control protein (albumin). rBPI21 (2 mg/kg body wt, BPI group) or a protein control preparation (burn group) in the same dose was administered in an intravenous bolus at 30 mins and 4 hrs after thermal injury. All animals were killed at 12 and 24 hrs postburn (six to ten rats for each interval). In addition, eight rats were taken as normal controls. MEASUREMENT AND MAIN RESULTS: Our data showed that treatment with rBPI21 was effective in preventing endotoxin translocation secondary to severe burns. Meanwhile, tissue lipopolysaccharide-binding protein, CD14, and tumor necrosis factor-alpha mRNA expression in various organs were inhibited markedly by rBPI21 secondary to acute insults (p <.05-.01). Furthermore, significant reduction in serum aminoleucine transferase concentrations and elevation in intestinal diamine oxidase activities in the rBPI21-treated group were found compared with controls (p <.05-.01). CONCLUSIONS: These findings indicate that endotoxin accumulated in local sites after thermal injury can markedly up-regulate lipopolysaccharide-binding protein/CD14 and tumor necrosis factor-alpha mRNA expression in various organs. Meanwhile, up-regulation of lipopolysaccharide-binding protein/CD14 expression would be the major molecular mechanism of increasing sensitivity to endogenous endotoxin response after burns. Early treatment with rBPI21may be effective in attenuating multiple organ damage resulting from gut-origin endotoxin translocation. This might be associated with the down-regulation effects of tissue lipopolysaccharide-binding protein and CD14 gene expression by the use of rBPI21.

Acute-Phase Proteins↗
PubMed2001

Restoration of normal ventricular electrophysiology in renovascular hypertensive rabbits after treatment with losartan.

Left ventricular hypertrophy (LVH) is associated with abnormal ventricular electrophysiology. We have shown complete regression of LVH and normalization of ventricular electrophysiology in renovascular hypertensive rabbits treated with captopril. To determine if angiotensin II type 1 receptor (AT1) blockade produces the same benefit, we treated hypertensive rabbits with losartan for 3 months. LVH was evaluated by heart-to-body weight ratio (HW/BW). Vulnerability to ventricular arrhythmia was assessed by ventricular fibrillation threshold (VFT) and dispersion of effective refractory period (ERP). The electrical properties of single left ventricular myocytes were characterized by action potential duration at 90% repolarization (APD90) and inward rectifier K+ current (I(K1)) density. Hypertensive rabbits treated with vehicle (LVH/Vehicle) had higher mean arterial pressure (MAP, 81+/-2 vs. 60+/-2 mm Hg) and HW/BW (2.71+/-0.07 vs. 1.97+/-0.04 g/kg), lower VFT (20+/-1 vs. 39+/-2 mA), larger dispersion of ERP (34+/-3 vs. 14+/-3 ms), longer APD90 (187+/-6 vs. 162+/-6 ms) and lower I(K1) density compared with control rabbits. Hypertensive rabbits treated with losartan (LVH/Losartan) had HW/BW (2.36+/-0.06 g/kg) between those of LVH/Vehicle and control rabbits, whereas MAP (65+/-2 mm Hg), VFT (34+/-2 mA), dispersion of ERP (19+/-1 ms), APD90 (160+/-6 ms), and I(K1) density were significantly different from LVH/Vehicle but similar to control. We conclude that AT1 blockade in renovascular hypertensive rabbits normalizes ventricular electrophysiology.

Action Potentials↗
PubMed2001

Perineural invasion as a predictor of biochemical outcome following radical prostatectomy for select men with clinically localized prostate cancer.

PURPOSE: The presence of perineural invasion on the prostate needle biopsy specimen has been suggested to be an independent predictor of prostate specific antigen (PSA) outcome following radical prostatectomy. We evaluated the clinical use of perineural invasion at biopsy for predicting time to PSA failure following radical prostatectomy after controlling for established prognostic factors. MATERIALS AND METHODS: A prospective evaluation using a Cox regression multivariate analysis of 750 men with clinically localized or PSA detected prostate cancer was performed to evaluate the ability of PSA, biopsy Gleason score, perineural invasion on the needle biopsy specimen and the percent of positive prostate biopsies to predict PSA outcome following radical prostatectomy. RESULTS: Multivariate analysis demonstrated that the presence of perineural invasion on the needle biopsy specimen provided additional information regarding 5-year PSA outcome (82% versus 95%, p = 0.04) for patients who were in the low risk group. This difference in PSA outcome could be explained by higher rates of positive surgical margins (25% versus 17%, p = 0.07). Patients whose prostate needle biopsy contained perineural invasion and who had the corresponding neurovascular bundle resected had a significantly lower positive margin rate (11% versus 100%, p = 0.001) compared to those who had the neurovascular bundle spared. The presence of perineural invasion on biopsy was not a significant predictor of PSA outcome following radical prostatectomy for patients in the intermediate or high risk group. CONCLUSIONS: Resection of the neurovascular bundle on the side corresponding to location of perineural invasion on the biopsy may decrease the positive surgical margin rate and improve outcome for low risk patients.

Adenocarcinoma↗
PubMed2001

Modulation of organ ICAM-1 expression during IV-TPN with glutamine and bombesin.

The gut primes neutrophils (PMNs) during injury, which can then induce distant organ damage after a second insult. ICAM-1 is an important adhesion molecule in PMN attachment to the vascular endothelium. Parenteral nutrition (TPN) decreases gut levels of interleukin (IL)-4 and IL-10, two cytokines that are normal inhibitors of ICAM-1 expression. TPN also increases gut ICAM-1 expression and PMN accumulation. Since glutamine (GLN) and bombesin (BBS) prevent TPN-associated impairment of mucosal immunity, we hypothesized that GLN and BBS would modulate organ ICAM-1 expression in association with normalization of IL-4 and IL-10 levels. Forty-four mice were fed chow, TPN, or GLN-TPN (isonitrogenous 2% GLN-enriched TPN). After 5 days of diets, ICAM-1 expression was quantified in organs using the dual radiolabeled monoclonal antibody technique. In the next experiment, 29 mice were fed chow, TPN, or BBS-TPN (BBS 15 microg/kg TID) for 5 days to measure organ ICAM-1 expression. Total IL-4 and IL-10 levels were measured with ELISA from intestinal homogenates of another set of 52 mice fed chow, TPN, GLN-TPN, or BBS-TPN. TPN significantly increased ICAM-1 expression in the lung, kidney, and intestine compared with chow mice. GLN-TPN decreased intestinal, but not lung, ICAM-1 expression, while BBS-TPN reduced pulmonary, but not gut, ICAM-1 levels. GLN- and BBS-TPN returned gut IL-4 levels to normal, but failed to increase IL-10 levels. GLN and BBS had different effects on organ ICAM-1 expression induced by lack of enteral nutrition. Mechanisms other than recovery of IL-4 alone may be responsible for gut ICAM-1 expression.

Animals↗
PubMed2001

TPN decreases IL-4 and IL-10 mRNA expression in lipopolysaccharide stimulated intestinal lamina propria cells but glutamine supplementation preserves the expression.

Total parenteral nutrition (TPN) decreases intestinal IgA and levels of Th2 cytokines, interleukin (IL)-4, and IL-10 within the supernatants of intestinal homogenates. These cytokines are known to stimulate IgA production in vitro by cells of the gut-associated lymphoid tissue (GALT). Glutamine (GLN) supplementation of TPN normalizes GALT mass and cytokine levels. Because intestinal homogenates contain mucosa which itself is a source of cytokines, it was unclear whether cytokines change within the GALT itself. This study investigates dietary effects on IL-4 and IL-10 cytokine mRNA expression within isolated GALT lamina propria cells after lipopolysaccharide (LPS) stimulation. Prospective randomized experimental trials were used in this study. Fifty-nine mice were randomized to chow, intravenous TPN (IV-TPN), intragastric TPN (IG-TPN), complex enteral diet (CED), or 2% GLN-supplemented TPN (GLN-TPN). In experiment 1, animals were fed chow, IV-TPN, IG-TPN, or CED for 5 days and received intraperitoneal LPS (100 microg/kg BW), and then were sacrificed 1 h later. Intestine was harvested for GALT lamina propria. Total RNA was extracted from lamina propria cells and cytokine mRNA for IL-4, and IL-10 was measured by reverse transcriptase polymerase chain reaction. IgA levels of intestinal washing were also measured with ELISA. In experiment 2, mRNA for IL-4 and IL-10, and intestinal IgA levels were measured in mice fed chow, IV-TPN, or GLN-TPN as in experiment 1. Both IL-4 and IL-10 mRNA expression decreased significantly in IV-TPN mice compared to chow or CED feeding. IG-TPN resulted in IL-10 mRNA expression significantly lower than chow or CED but significantly better than IV-TPN. GLN preserved IL-4 and IL-10 mRNA levels, which correlated with intestinal IgA levels. Route and type of nutrition as well as GLN influence message for the Th2 type IgA-stimulating cytokines, IL-4 and IL-10, within the primary site of GALT IgA production, the lamina propria.

Animal Feed↗
PubMed2001

Analysis and expression of the alpha-expansin and beta-expansin gene families in maize.

Expansins comprise a multigene family of proteins in maize (Zea mays). We isolated and characterized 13 different maize expansin cDNAs, five of which are alpha-expansins and eight of which are beta-expansins. This paper presents an analysis of these 13 expansins, as well as an expression analysis by northern blotting with materials from young and mature maize plants. Some expansins were expressed in restricted regions, such as the beta-expansins ExpB1 (specifically expressed in maize pollen) and ExpB4 (expressed principally in young husks). Other expansins such as alpha-expansin Exp1 and beta-expansin ExpB2 were expressed in several organs. The expression of yet a third group was not detected in the selected organs and tissues. An analysis of expansin sequences from the maize expressed sequence tag collection is also presented. Our results indicate that expansin genes may have general, overlapping expression in some instances, whereas in other cases the expression may be highly specific and limited to a single organ or cell type. In contrast to the situation in Arabidopsis, beta-expansins in maize seem to be more numerous and more highly expressed than are alpha-expansins. The results support the concept that beta-expansins multiplied and evolved special functions in the grasses.

Amino Acid Sequence↗
PubMed2001

Modification of expansin transcript levels in the maize primary root at low water potentials.

We previously demonstrated that maintenance of cell elongation in the apical region of maize primary roots at low water potentials (psi(w)) was associated with an increase in expansin activity and extractable expansin protein. Here, we characterized the spatial pattern of expansin gene expression along the growing maize root and studied the effect of low psi(w) on expansin gene expression. Roots were divided into three segments: apical 0 to 5 mm, subapical 5 to 10 mm, and non-growing 10 to 20 mm. Of the five expansin genes expressed in control roots, two alpha-expansins (Exp1 and Exp5) and two beta-expansins (ExpB2 and ExpB8) are expressed specifically in the growing region, whereas expression of beta-expansin ExpB6 is shifted basipetally. After seedlings were transplanted to vermiculite with a psi(w) of -1.6 MPa, transcripts for Exp1, Exp5, and ExpB8 rapidly accumulated in the apical region of the root. These mRNA changes correlated with the maintenance of root elongation and increases in wall extensibility found previously. The beta-expansins ExpB2 and ExpB6 showed distinctive patterns of expression and responses to low psi(w,) indicative of distinctive functions. Inhibition of abscisic acid (ABA) accumulation at low psi(w) (by fluridone treatment) had no effect on expansin expression, except that ExpB2 transcript level showed a minor dependence on ABA. Gene-specific regulation of alpha- and beta-expansin mRNA pools likely contributes to growth alterations of the maize (Zea mays) root as it adapts to a low psi(w), but these changes do not appear to be mediated by changes in ABA content.

Abscisic Acid↗
PubMed2001

A fungal endoglucanase with plant cell wall extension activity.

We have identified a wall hydrolytic enzyme from Trichoderma reesei with potent ability to induce extension of heat-inactivated type I cell walls. It is a small (23-kD) endo-1,4-beta-glucanase (Cel12A) belonging to glycoside hydrolase family 12. Extension of heat-inactivated walls from cucumber (Cucumis sativus cv Burpee Pickler) hypocotyls was induced by Cel12A after a distinct lag time and was accompanied by a large increase in wall plasticity and elasticity. Cel12A also increased the rate of stress relaxation of isolated walls at very short times (<200 ms; equivalent to reducing t(0), a parameter that estimates the minimum relaxation time). Similar changes in wall plasticity and elasticity were observed in wheat (Triticum aestivum cv Pennmore Winter) coleoptile (type II) walls, which showed only a negligible extension in response to Cel12A treatment. Thus, Cel12A modifies both type I and II walls, but substantial extension is found only in type I walls. Cel12A has strong endo-glucanase activity against xyloglucan and (1-->3,1-->4)-beta-glucan, but did not exhibit endo-xylanase, endo-mannase, or endo-galactanase activities. In terms of kinetics of action and effects on wall rheology, wall loosening by Cel12A differs qualitatively from the action by expansins, which induce wall extension by a non-hydrolytic polymer creep mechanism. The action by Cel12A mimics some of the changes in wall rheology found after auxin-induced growth. The strategy used here to identify Cel12A could be used to identify analogous plant enzymes that cause auxin-induced changes in cell wall rheology.

Biomechanical Phenomena↗
PubMed2001

Implementing multiple static field delivery for intensity modulated beams.

A clinically oriented two-dimensional intensity-modulated beam delivery method is implemented using multiple static segmented fields, i.e., the "step-and-shoot" approach. Starting with a desired al" intensity distribution, it creates a multiple-level intensity approximation, and then constructs a sequence of segmented fields to deliver the multiple-level intensities using multileaf collimator (MLC) and independent backup jaws. The approach starts with a simple grouping of all the nonzero intensity values into a minimum number of clusters for a user specified deviation tolerance for the ideal plan. The k-means clustering algorithm is then employed to find the optimal levels of intensity that minimize the discrepancies between the ideal and the approximated intensities, without violating the user specified deviation tolerance. The multiple-level intensities are then decomposed into a sequence of machine deliverable segments. Apart from the first segment for each gantry angle, all the other segments are arranged to minimize the total travel distance of the leaves. The first segment covers the entire irradiated area and is used for treatment verification by electronic portal imaging. The implementation issues due to the physical constraints of the MLCs are also addressed.

Algorithms↗
PubMed2001

Induction of epithelial cell death including apoptosis by enteropathogenic Escherichia coli expressing bundle-forming pili.

Infection with enteropathogenic Escherichia coli (EPEC) is a major cause of severe infantile diarrhea, particularly in parts of the developing world. The bundle-forming pilus (BFP) of EPEC is an established virulence factor encoded on the EPEC adherence factor plasmid (EAF) and has been implicated in both localized adherence to host cells and bacterial autoaggregation. We investigated the role of BFP in the ability of EPEC binding to kill host epithelial cells. BFP-expressing strains killed all three cell lines tested, comprising HEp-2 (laryngeal), HeLa (cervical), and Caco-2 (colonic) cells. Analysis of phosphatidylserine expression, internucleosomal cleavage of host cell DNA, and morphological changes detected by electron microscopy indicated evidence of apoptosis. The extent of cell death was significantly greater for BFP-expressing strains, including E2348/69, a wild-type clinical isolate, as well as for a laboratory strain, HB101, transformed with a bfp-carrying plasmid. Strains which did not express BFP induced significantly less cell death, including a bfpA disruptional mutant of E2348/69, EAF plasmid-cured E2348/69, HB101, and HB101 complemented with the locus of enterocyte effacement pathogenicity island. These results indicate a direct correlation between BFP expression and induction of cell death, including apoptosis, an event which may involve the targeting of host cell membrane phosphatidylethanolamine.

Apoptosis↗
PubMed2001

Alteration of Cx43:Cx40 expression ratio in A7r5 cells.

Connexins (Cx) 40 and 43 are coexpressed by several cell types at ratios that vary as a function of development, aging, and disease. Because these connexins form heteromeric channels, changes in expression ratio might be expected to significantly alter the connexin composition of the gap junction channel population and, therefore, gap junction function. To examine this possibility, we stably transfected A7r5 cells, which naturally coexpress Cx43 and Cx40, with a vector encoding antisense Cx43. Cx43 mRNA continued to be expressed in the antisense transfected clones, although levels were inversely related to the number of copies of antisense DNA incorporated into the genome. Protein levels, quantified in the clones with the highest and lowest Cx43:Cx40 mRNA ratios, were not well predicted by the mRNA levels, although the trends predicted by the Cx43:Cx40 mRNA ratio were preserved. Electrical coupling did not differ significantly between clones, but the clone with elevated Cx43:Cx40 protein expression ratio and unchanged Cx43 banding pattern was significantly better dye coupled than the parental A7r5 cells. These results suggest that as the Cx43:Cx40 ratio increases, provided alterations of Cx43 banding pattern (phosphorylation) have not occurred, permeability to large molecules increases even though electrical coupling remains nearly constant.

Antisense Elements (Genetics)↗