Biomedical subjects

J Sun

Publications and source records attributed to J Sun.

750 records · Page 42Linked to original sources

PubMedDate not supplied

Sensitive biomarker of polycyclic aromatic hydrocarbons (PAHs): urinary 1-hydroxyprene glucuronide in relation to smoking and low ambient levels of exposure.

The study was conducted in a Chinese population with occupational or environmental exposures to polycyclic aromatic hydrocarbons (PAHs). A total of 106 subjects were recruited from coke-oven workers (workers), residents in a metropolitan area (residents) and suburban gardeners (gardeners). All subjects were monitored twice for their personal exposures to PAHs. The biological samples were collected for measurements of 1-hydroxypyrene (1-OHP) and cotinine in urine. The geometric means of personal exposure levels of pyrene, benz(a)anthracene (BaA) and benzo(a)pyrene (BaP) in workers were 1.470, 0.978 and 0.805 microg m-3, respectively. The corresponding levels in residents were 0.050, 0.034 and 0.025 microg m-3; and those in gardeners were 0.011, 0.020 and 0.008 microg m-3, respectively. The conjugate of 1-OHP with glucuronide (1-OHP-G) is the predominant form of pyrene metabolite in urine and it showed strong associations with exposures not only to pyrene, but also to BaA, BaP and total PAHs. Most importantly, a significant difference in 1-OHP-G was even detected between the subgroups with exposures to BaP at < 0.010 and > 0.010 but < 0.020 microg m-3, suggesting that 1-OHP-G is a good marker that can be used for the risk assessment of BaP exposure at levels currently encountered in ambient air. Furthermore, multiple regression analyses of 1-OHP-G on PAHs exposure indicated that cigarette smoke was a major confounding factor and should be considered and adjusted for while using 1-OHP to estimate PAHs exposure.

Air Pollutants↗

PubMedDate not supplied

Complementation analyses of Pseudomonas solanacearum extracellular polysaccharide mutants and identification of genes responsive to EpsR.

Many plant-pathogenic bacteria require extracellular polysaccharides (EPS) for successful infection. For example, mutations tht prevent EPS production in the bacterial wilt pathogen, Pseudomonas solanacearum, will reduce the ability to wilt plants. While several P. solanacearum EPS genes have been identified and characterized, a systematic analysis of EPS mutants has not previously been performed. We have screened over 12,000 transposon-tagged mutants and categorized 66EPS::lacZ mutants into nine complementation sets. Five of these are composed of previously characterized EPS structural and regulatory loci; four contain newly described EPS loci. One of the four novel complementation sets has been determined to be defective for both EPS and lipopolysaccharide production. We also used the EPS::lacZ mutants to examine the interaction between P. solanacearum EPS genes. Overexpression of the previously described regulator EpsR was found to down-regulate the expression of genes encoding production of the major acidic form EPS.

Bacterial Proteins↗

PubMedDate not supplied

Reduced capacity of whole blood leucocytes to express tumour necrosis factor-alpha and interleukin-10 following major orthopaedic surgery.

BACKGROUND: Severe trauma is a challenge to the immune response and may cause reduced immune capacity. As a marker of decreased cellular activity, studies with ex vivo lipopolysaccharide (LPS) stimulation of whole blood or isolated mononuclear cells from injured patients have revealed reduced production of inflammatory cytokines. To gain further insight into immune alterations in orthopaedic surgery, we studied LPS-induced tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 in whole blood of patients during peri- and postoperative phases of total hip replacement. METHODS: Four females and 3 males undergoing elective total hip replacement were included in the study. Ex vivo LPS-induced TNF-alpha and IL-10 were measured in a whole blood assay before, during and at 1 and 6 days after operation. In addition, the counts of white blood cells were determined. RESULTS: During the operation, there were significant reductions in the number of monocytes, but at day 1 and 6 after surgery, there were significant increases as compared to the levels before surgery. The capacity of whole blood to express TNF-alpha and IL-10 did not change significantly during the operation and the following postoperative day. At day 6, however, there were significant reductions in expression of both TNF-alpha and IL-10 as compared to the levels before the operation. In relation to the values of monocytes, there was a significant reduction in the expression of TNF-alpha also at day 1 after operation. CONCLUSION: Our data indicate that in the course of at least 6 days after a major orthopaedic trauma, there is suppression of the whole blood capacity to express the inflammatory cytokine TNF-alpha and the anti-inflammatory cytokine IL-10 when exposed to LPS. During this time, then, the patient is particular susceptible to septic complications.

Adult↗

PubMedDate not supplied

Cardiomyocyte transplantation in a porcine myocardial infarction model.

Transplantation of cardiomyocytes into the heart is a potential treatment for replacing damaged cardiac muscle. To investigate the feasibility and efficiency of this technique, either a cardiac-derived cell line (HL-1 cells), or normal fetal or neonatal pig cardiomyocytes were grafted into a porcine model of myocardial infarction. The myocardial infarction was created by the placement of an embolization coil in the distal portion of the left anterior descending artery in Yorkshire pigs (n = 9). Four to 5 wk after creation of an infarct, the three preparations of cardiomyocytes were grafted, at 1 x 10(6) cells/20 microL into normal and into the middle of the infarcted myocardium. The hearts were harvested and processed for histologic examinations 4 to 5 wk after the cell grafts. Histologic evaluation of the graft sites demonstrated that HL-1 cells and fetal pig cardiomyocytes formed stable grafts within the normal myocardium without any detrimental effect including arrhythmia. In addition, a marked increase in angiogenesis was observed both within the grafts and adjacent host myocardium. Electron microscopy studies demonstrated that fetal pig cardiomyocytes and the host myocardial cells were coupled with adherens-type junctions and gap junctions. Histologic examination of graft sites from infarct tissue failed to show the presence of grafted HL-1 cells, fetal, or neonatal pig cardiomyocytes. Cardiomyocyte transplantation may provide the potential means for cell-mediated gene therapy for introduction of therapeutic molecules into the heart.

Animals↗

PubMedDate not supplied

Comparison of porcine hepatocytes with human hepatoma (C3A) cells for use in a bioartificial liver support system.

Cells from primary porcine hepatocytes (PPH) and the immortalized human hepatoma cell line C3A are both used in bioartificial liver support systems (BALSS). In this work the viability and metabolic capacity of PPH and C3A cells cultured in different media were compared. Also, because the cells come into direct or indirect contact with human blood components in BALSS, the effects of human complement on survival and functions of the cells was evaluated. For short-term culture, maintenance of PPH viability was essential for retention of P450IA1 activity (r = 0.882, p < 0.01) and effective ammonia clearance (r = -0.791, p < 0.01). When cell viability was below 60% P450IA1 activity could not be recorded and nitrogen elimination activity significantly diminished. In contrast to PPH, ammonia levels were markedly increased for C3A cells in all culture media tested (p < 0.01). Ammonia increase correlated with C3A viability (r = 0.896, p < 0.05). PPH metabolic function was superior to that of the C3A cell line when evaluated by P450IA1 activity, ammonia removal, and amino acid metabolism. When PPH were incubated in human plasma (HP) or human serum (HS) there was rapid and irreversible deterioration of viability occurring within 9 h. This toxic effect could be prevented by the inactivation of complement. When sodium citrate dissolved in dextrose was added to medium, there was considerable damage to both PPH and the C3A cell line. However, there was no demonstrable toxic effect when hepatic cells of either type were exposed to heparin. We conclude that PPH cultivated in complement-inactivated HP or HS are to be preferred to C3A for clinical application of BALSS, and that heparin should be preferred for anticoagulation in BALSS.

Amino Acids↗

PubMedDate not supplied

Adsorption-induced antigenic changes and their significance in ELISA and immunological disorders.

The functional properties of 125I-labeled antibodies and antigens adsorbed on polystyrene and silicone were compared to their counterparts immobilized by non-adsorptive methods. Less than 20% of polyclonal (pAb) and 1-2% of monoclonal (mAb) capture antibody equivalents remained functional after adsorption as a monolayer. Survivability circa doubled or was totally rescued, when the same antibodies were immobilized via a streptavidin bridge or by using a first stage polyclonal antiglobulin capture antibody, respectively. Similarly, the antigenicity of bovine IgGs for pAb and mAb anti-IgGs was highest when the IgGs were immobilized via a streptavidin bridge or when secondarily adsorbed to an albumin monolayer. IgGs in these configurations were significantly more antigenic than when directly adsorbed on polystyrene or a silicone elastomer. Similar activity was seen after adsorption on polystyrene or silicone. Interestingly, these IgGs were equally antigenic when denatured and subsequently adsorbed in 6M guanidine-HCl versus adsorption in PBS without prior denaturation. Although many of the above finding on antibodies and antigens could be explained by the greater accessibility of antigenic epitopes or antibody binding sites when molecules are immobilized by some type of underlying molecular layer, we also show that certain mAb and pAbs preferentially recognized allotopes on IgG2a when IgG2a was adsorbed. Furthermore, such antigenicity was highest when IgG2a was adsorbed at low, sub-monolayer concentrations. Finally, we show that differences in antigenicity need not be related to the method of immobilization, but can also result from differences in the microenvironment of the epitope. This was demonstrated using a filamentous phage clone specific for fluorescein (FLU). This clone recognizes the fluorescein hapten differently depending on the carrier protein used and the method of conjugation. Data presented in this report indicate that antibodies and antigens adsorbed on hydrophobic polymers undergo changes in their functional properties. Data suggest that both changes in conformation and the accessibility of antigen epitopes or antibody binding sites, most likely occur. Especially in the case of the latter, the functional concentration may be 1-2 orders of magnitude lower than the antibody protein concentration. These observations have implications for immunodiagnostics and emphasize the need to determine the specificity of an antibody in the assay in which it is employed and to make no assumptions about the behavior of solid-phase antigens and antibodies from their behavior in solution. Our studies are also relevant to the use of silicone medical prostheses. The antigenicity of IgGs adsorbed on silicone as a multilayer (secondary layer) is much higher than when directly adsorbed. Since such surfaces would be exposed to very high protein concentrations in vivo, multilayers not a monolayer, would be expected. Thus it would seem from these studies that host protein adsorbed on silicone would be expressed to the immune system at the surface of multilayers. This being the case, it seems unlikely that the adsorption of host protein in vivo would generate new epitopes against which the host's immune system could respond and subsequently initiate an autoimmune syndrome.

Adsorption↗

PubMedDate not supplied

Liquid chromatographic determination of carotenoids and vitamins A and E in multivitamin tablets.

Carotenoids and vitamins A and E in multivitamin tablets can be determined simultaneously by reversed-phased liquid chromatography (LC) with a programmable UV detector. Samples were dissolved in dimethyl sulfoxide and then extracted with hexane. A portion was injected onto a Symmetry C18, 150 x 4.6 mm id, 5 microns column and chromatographed with a mobile phase of acetonitrile--0.25% ammonium acetate in methanol and 0.05% triethylamine in dichloromethane. A step gradient was used. The system was operated at 25 degrees C with a flow rate of 1.5 mL/min. UV detection was at 325 nm for retinols, 285 nm for tocopherols, and 450 nm for carotenoids. Detection limits were less than 0.3 ng for retinol and retinyl acetate; 2 ng for alpha-tocopherol acid succinate; 10 ng for alpha-tocopherol, gamma-tocopherol, and alpha-tocopherol acetate; and 0.4 ng for alpha-carotene and beta-carotene. Intraday and interday coefficients of variation ranged from 1.40 to 5.20%. The sample preparation method and LC assay are practical for quality control and routine analysis of multivitamin tablets.

Carotenoids↗

PubMedDate not supplied

Analysis of multivariables during porcine liver digestion to improve hepatocyte yield and viability for use in bioartificial liver support systems.

In order to achieve optimal BALSS function, preparation of porcine hepatocytes with high yield, viability, and P450 activity is known to be important. To date hepatocyte yields have varied from 0.58 x 10(10) to 3.45 x 10(10) and viabilities from 75% to 95% within and between laboratories, even when using the same digestion methods and procedures, indicating that hepatocyte isolation during porcine liver digestion is not fully optimized. The aim of this work was to identify the critical parameters affecting cell recovery during porcine liver harvesting by investigating 21 variables involved in the process, including pig body and liver weight, different digestion times of perfusates, pH, a range of concentrations of sodium and chloride in EDTA, and collagenase perfusates. Univariate and multivariate analysis of a retrospective study (n = 23) revealed that low perfusate pH during the process of digestion had a positive effect on hepatocyte yield (p < 0.05), while high (relative) concentrations of sodium and chloride in the perfusates had significant negative effects on hepatocyte viability (both p < 0.05). Sodium and chloride had narrow optimal ranges for achieving a >90% viability. These findings were then tested in a prospective study (n = 10) and further verified. High hepatocyte viabilities (91.8+/-1.6% p = 0.036) and yields (2.56+/-0.48 x 10(10)) were achieved consistently, and P450IA1 activity was increased after sodium and chloride concentrations and pH in the perfusates were controlled. The physiological mechanism by which sodium and chloride affects hepatocyte viability during porcine liver digestion is discussed.

Animals↗

PubMedDate not supplied

Androgen deprivation induces selective outgrowth of aggressive hormone-refractory prostate cancer clones expressing distinct cellular and molecular properties not present in parental androgen-dependent cancer cells.

PURPOSE: The mechanism of progression of human prostate cancer (CaP) cells under androgen ablation therapy remains unclear. To study the alternative pathways of CaP cell growth under conditions of androgen deprivation, androgen-independent CaP variants were selected and expanded from an androgen-dependent CaP line via an in vitro androgen deprivation treatment. Cellular and molecular properties of these androgen-independent variants were characterized both in vitro and in vivo and compared with those of their parental androgen-dependent cells. METHODS: Androgen deprivation treatment of an androgen-dependent CaP cell line, LNCaP, was carried out by replacing culture medium with RPMI 1640 medium plus 10% charcoal-stripped serum. Cells that survived through the androgen deprivation treatment were harvested and expanded in the androgen-deficient culture medium and were designated CL-1. The CL-1 cells were also recultured in androgen-containing medium and designated CL-2. The growth (cell cycle analysis, 3H-thymidine incorporation assay, growth expansion, and colonization efficiency), expression of CaP-associated markers (semiquantitative reverse transcriptase polymerase chain reaction), interaction with endothelial and bone marrow stromal cells, sensitivity to anticancer agents and radiation (growth inhibition), and tumorigenicity of CL-1 and CL-2 cells were determined and compared with these characteristics in parental LNCaP cells. RESULTS: CL-1 and CL-2 cells are fast-growing cells when compared with parental LNCaP cells. They were capable of potentiating the growth of endothelial and bone marrow stromal cells in co-culture experiments and acquired significant resistance to radiation and to anticancer cytotoxic agents (Taxol paclitaxel, vinblastine, and etoposide). In contrast to the poorly tumorigenic parental LNCaP cells, CL-1 and CL-2 lines proved highly tumorigenic, exhibiting invasive and metastatic characteristics in intact and castrated mice or in female mice within a short period of 3 to 4 weeks. No growth supplements (e.g., Matrigel) were needed. When transfected with the green fluorescence protein (GFP) gene and transplanted orthotopically in the accessory sex gland, extensive metastatic disease from the primary CL tumor could be identified in bone, lymph nodes, lung, liver, spleen, kidney, and brain. Semiquantitative reverse transcriptase polymerase chain reaction analysis revealed a markedly distinct molecular expression profile in the CL lines: overexpression of basic fibroblast growth factor, interleukin-6, interleukin-8, vascular endothelial growth factor, transforming growth factor-beta, epidermal growth factor receptor, caveolin, and bcl-2 messenger RNAs and marked down-regulation of E-cadherin, p-53, and pentaerythritol tetranitrate. CONCLUSIONS: Early administration of hormonal therapy after failure of first-line treatment is associated with a profound clonal selection of aggressive AI variants, such as CL-1 and CL-2 lines. These tumor lines, with their parental counterparts, can serve as valuable tools for studying the cellular and molecular mechanisms of CaP progression and metastasis under hormonal therapy. CL-1 and CL-2 offer a unique and reproducible model for the evaluation of drug sensitivity and for other therapeutic modalities for advanced prostate cancer.

Androgens↗

PubMedDate not supplied

Simultaneous determination of E- and Z-guggulsterones in dietary supplements containing Commiphora mukul extract (guggulipid) by liquid chromatography.

Guggulipid, the standardized product from the extraction of the ole-gum-resin from the Commiphora mukul plant, has been marketed as a hypolipidemic agent. The ketosteroids, cis- and trans-4,17(20)-pregnadiene-3,16-dione, known as E- and Z-guggulsterones, respectively, are the main ingredients in guggulipid. A liquid chromatographic method was developed for simultaneous determination of E- and Z-guggulsterones in guggulipid preparations using synthetic E- and Z-guggulsterone standards. Realtively low amounts of guggulsterones (E and Z) were found in commercial guggulipid preparations in comparison with the manufacturer's claim of 2.5%. The mixture of E- and Z-guggulsterones was extracted and separated on a Symmetry C18 reversed-phase column, with a mobile phase of acetonitrile--water (46 + 54, v/v) and detected at 242 nm. The retention times of E- and Z-guggulsterones are approximately 8 and 11 min, respectively. Assay quantitation was based on the calibration curve obtained from a mixture of synthetic standard E- and Z-guggulsterones. Experimental data on selectivity, linearity, accuracy, and recoveries are presented.

Chromatography, Liquid↗

PubMedDate not supplied

Kinematic analysis of locomotion in unilateral vestibular neurectomized cats.

The vestibular syndrome following unilateral lesion of the vestibular system and the subsequent behavioral compensation over time have been well documented in many species. However, the locomotor pattern changes and the behavioral strategies used to preserve balance have still not been described. This study was aimed at quantitatively describing posturolocomotor behavior in cats tested before and after unilateral vestibular neurectomy (UVN) by the rotating beam test, which provides locomotor tasks of various difficulty. The position of head, neck, and trunk and the trajectory of the forelimbs and hindlimbs were recorded in 5 cats by 3D motion analysis. Step length and frequency walking velocity, and body height were computed. Results showed that normal cats adapted their locomotor patterns to the speed of beam rotation by increasing step length and/or frequency, that is, by increasing walking velocity, but without drastically changing their body posture. By contrast, UVN cats typically lowered their body centers of gravity and modified their locomotor patterns according to the locomotor task. Mean walking velocity was decreased in the low range of beam rotation as a result of smaller step length and lower frequency, and it was increased in the high range by opposite effects on these step cycle parameters. Modifications of the locomotor parameters were a function of the direction of beam rotation, showing significant reduction of step length, frequency, and velocity in the low range of counterclockwise compared to clockwise beam rotation, that is, during rotations toward the lesioned side. Phase plane plots of foot linear velocity with respect to foot linear displacement along the horizontal longitudinal axis displayed two different limit cycles, adapted to easy (low range of beam rotation) and more difficult (high range of rotation) walking conditions, in the normal cat. These dynamic profiles of the trajectories of the limbs during the step cycle were not greatly modified after vestibular lesion, but the phase plane typically observed in the high range for the normals was also found in the low range for the UVN cats. Thus, locomotor equilibrium function in the cat is strongly impaired following UVN, but locomotor balance can still be achieved in the UVN cats by the development of adaptive posturolocomotor strategies compensating for the lack of vestibular inputs.

Animals↗

PubMedDate not supplied

The effect of promoter strength in adenoviral vectors containing herpes simplex virus thymidine kinase on cancer gene therapy in vitro and in vivo.

The use of adenoviral vectors to deliver the herpes simplex virus thymidine kinase (HSVtk) gene followed by treatment with the prodrug ganciclovir (GCV) has promise for a variety of applications where excess cell proliferation is detrimental such as treatment of tumors and vascular restenosis. Optimizing this system is thus an important goal. The purpose of this study was to determine if the induction of higher levels of HSVtk expression would augment the sensitivity to GCV. This was accomplished by generating adenoviral vectors that expressed HSVtk from promoters of different efficiencies (the CMV versus RSV promoters). Despite higher levels of HSVtk expression per cell with the CMV promoter, there was no significant enhancement of antitumor effects between RSV- and CMV-driven adenovirus vectors in in vitro and in vivo studies indicating that simply increasing HSVtk enzyme levels per cell above a minimal threshold level will not be effective in augmenting the HSVtk/GCV system. These results suggest that other strategies, e.g., the use of higher doses of GCV, augmentation of the "bystander effect," the generation of mutant HSVtk genes with higher substrate affinities, the discovery of improved vectors with increased transduction efficiencies, or the development of new prodrugs with higher affinities for HSVtk will therefore be needed to enhance therapeutic responses.

Adenoviridae↗