Biomedical subjects

L Tang

Publications and source records attributed to L Tang.

At least 19 recordsLinked to original sources

PubMed2006

Surface morphology and adsorbed proteins affect phagocyte responses to nano-porous alumina.

This study evaluates human neutrophil responses to aluminum oxide membranes with different pore sizes (20 nm and 200 nm in diameter) uncoated and pre-coated with serum, collagen I, or fibrinogen. The effect of released neutrophil granule components on the survival of osteoblastic cells (MG63) bound to the alumina membranes has also been evaluated. Without protein coatings the 20 nm pore-size membranes prompt higher reactive oxygen species (ROS) production as assessed by luminol-amplified chemiluminescence than the 200 nm pore-size membranes. Such pore-size depending responses were also found on membranes pre-coated with fibrinogen, but not with collagen or serum were in fact a much lower ROS production was observed. In addition, uncoated and fibrinogen-coated membranes prompt stronger release of the granule enzymes, myeloperoxidase and elastase, than collagen or serum-coated alumina. Equally important, we found that surface-mediated phagocyte activation and the subsequent release of granule components had a significant affect on the adhesion, viability and proliferation of osteoblasts. This stresses the importance of studying not only cell/surface interactions but also cell/cell interactions in wound healing and tissue regeneration processes.

Adsorption↗

PubMed2006

Biomass production and carbon sequestration potential in poplar plantations with different management patterns.

Biomass production and carbon storage in short-rotation poplar plantations over 10 years were evaluated at the Hanyuan Forestry Farm, Baoying County, China. Experimental treatments applied in a split-plot design included four planting densities (1111, 833, 625 and 500 stems ha(-1)) and three poplar clones (NL-80351, I-69 and I-72). Based on the model of total biomass production developed, total plantation biomass production was significantly different in the plantations. The ranking of the plantation biomass production by planting density was 1111>833 more more than 625>500 stems ha(-1), and by components was stem>root>or=branch>leaf for all plantations. At 10 years, the highest total biomass in the plantation of 1111 stems ha(-1) reached about 146 t ha(-1), which was 5.3%, 11.6% and 24.2% higher than the plantations of 833, 625 and 500 stems ha(-1), respectively. The annual increment of biomass production over 10 years differed significantly among initial planting densities and stand ages (p<0.01), but no significant difference was observed from age 7 to 10. Mean carbon concentration among all biomass components ranged from 42-50%, with the highest carbon concentrations in stems and the lowest in leaves. Over the study period, the dynamic pattern of total plantation carbon storage by planting density was similar to that of total biomass production. At age 10, the highest total plantation carbon storage in the plantation of 1111 stems ha(-1) reached about 72.0 t ha(-1), which was 5.4%, 11.9% and 24.8% higher than in the plantations of 833, 625 and 500 stems ha(-1), respectively. The annual carbon storage increment over 10 years differed significantly among initial planting densities and stand ages (p<0.01), and it showed a pattern similar to the annual biomass production increment of the plantations. The results suggest that biomass production and carbon storage potential were highest for planting densities of 1111 and 833 stems ha(-1) grown over 5- and 6-year cutting cycles, respectively. If 3- or 4-year cutting cycles are used, the planting density should be higher than 1111 stems ha(-1) (e.g., 1667 or 2500 stems ha(-1)). Based on the mean annual carbon storage for the plantation of 625 stems ha(-1), as an estimation, the mean carbon storage in the biomass of poplar plantations (excluding leaves) amounts to 3.75x10(7) t ha(-1)yr(-1) in China.

Biomass↗

PubMed2006

Comparative acute and combinative toxicity of aflatoxin B1 and fumonisin B1 in animals and human cells.

Aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) are important food-borne mycotoxins. The co-contamination of food stuffs with these two mycotoxins is well known and has been possibly implicated in the development of human hepatocellular carcinoma in high risk regions around the world. In this study the acute and combinative toxicity of AFB(1) and FB(1) were tested in F-344 rats, mosquitofish (Gambusia affinis), immortalized human hepatoma cells (HepG2) and human bronchial epithelial cells (BEAS-2B). Preliminary experiments were conducted in order to assess the acute toxicity and obtain LD(50), LC(50) and IC(50) values for individual toxins in each model, respectively. This was followed by testing combinations of AFB(1) and FB(1) to obtain LD(50), LC(50) and IC(50) values for the combination in each model. All models demonstrated a significant dose response in relation to toxin treatment. The potency of the mixture was gauged through the determination of the interaction index metric. Results of this study demonstrate that these two toxins interacted to produce alterations in the toxic responses with a strong additive interaction noted in the cases of F344 rats and mosquitofish. It can be gathered that this combination may pose a significant threat to public health and further research needs to be completed addressing alterations in metabolism and detoxification that may influence the toxic manifestations in combination. These results will provide foundational knowledge for future studies on long-term combinative toxic and health effects of these mycotoxins.

Aflatoxin B1↗

PubMed2005

Anion adsorption induced reversal of coherency strain.

Experimental results are presented for stress evolution, in vacuum and electrolyte, for the first monolayer of Cu on Au(111). In electrolyte the monolayer is pseudomorphic and the stress-thickness change is -0.60 N/m, while conventional epitaxy theory predicts a value of +7.76 N/m. In vacuum, the monolayer is incoherent with the underlying gold. Using a combination of first-principles based calculations and molecular dynamic simulations we analyzed these results and demonstrate that in electrolyte, overlayer coherency is maintained owing to anion adsorption.

Journal Article↗

PubMed2005

The role of thrombin in gliomas.

BACKGROUND: In a previous study we found that intracerebral infusion of argatroban, a specific thrombin inhibitor, reduces brain edema and neurologic deficits in a C6 glioma model. OBJECTIVES: To examine the role of thrombin in gliomas and whether systemic argatroban administration can reduce glioma mass and neurologic deficits and extend survival time in C6 and F98 gliomas. METHODS: The presence of thrombin in human glioblastoma samples and rat C6 glioma cells (in vitro and in vivo) was assessed using immunohistochemistry. The effect of thrombin on C6 cell proliferation in vitro was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. The role of thrombin in vivo was assessed in rat C6 and F98 glioma cell models using argatroban, a thrombin inhibitor. The effects of argatroban on tumor mass, neurologic deficits and survival time were investigated. RESULTS: Thrombin immunoreactivity was found in cultured rat C6 glioma cells and human glioblastomas. Thrombin induced C6 cell proliferation in vitro. In C6 glioma, argatroban reduced glioma mass (P < 0.05) and neurologic deficits (P < 0.05) at day 9. In F98 glioma, argatroban prolonged survival time (P < 0.05). CONCLUSION: These results suggest that thrombin plays an important role in glioma growth. Thrombin may be a new therapeutic target for gliomas.

Animals↗

PubMed2005

Short-term safety evaluation of processed calcium montmorillonite clay (NovaSil) in humans.

NovaSil clay (NS) provides significant protection from the adverse effects of aflatoxins (AFs) in multiple animal species by decreasing bioavailability from the gastrointestinal tract. It is postulated that NS clay can be safely added to human diets to diminish exposure and health risks from AF contaminated food. To determine the safety and tolerance of NS in humans and establish dosimetry protocols for long-term efficacy studies, a randomized and double-blinded phase I clinical trial was conducted. Volunteers (20-45 yr in age), were clinically screened for confirmation of their health status. Fifty subjects (23 males and 27 females) were randomly divided into two groups: The low-dose group received nine capsules containing 1.5 g/day, and the high-dose group received nine capsules containing 3.0 g/day for a period of 2?wk. NS capsules were manufactured in the same color and size and were distributed to each participant three times a day at designated sites where follow-up was taken to record any side effects and complaints. Blood and urine samples were collected before and after the study for laboratory analysis. All participants completed the trial and compliance was 99.1%. Mild GI effects were reported in some participants. Symptoms included abdominal pain (6%, 3/50), bloating (4%, 2/50), constipation (2%, 1/50), diarrhea (2%, 1/50), and flatulence (8%, 4/50). No statistical significance was found between the two groups for these adverse effects (p > 0.25). No significant differences were shown in hematology, liver and kidney function, electrolytes, vitamins A and E, and minerals in either group. These results demonstrate the relative safety of NS clay in human subjects and will serve as a basis for long-term human trials in populations at high risk for aflatoxicosis.

Administration, Oral↗

PubMed2005

Evaluation of heavy metal inhibition of activated sludge by TTC and INT-electron transport system activity tests.

TTC and INT-electron transport system activity tests were compared for assessing heavy metal inhibition of activated sludge. The median inhibitory concentrations (IC50s) of Cu2+, Zn2+, Cd2+, Hg2+, Ni2+, Pb2+ and Ag+ measured via TTC test were lower than those measured via INT test, which indicates that the INT-electron transport system activity test was less sensitive to heavy metal toxicity than the TTC test. Tested heavy metals brought about similar decrease in TTC-electron transport system activity and COD removal rate, but less decrease in INT-electron transport system activity than COD removal rate, which suggests that the TTC-electron transport system activity is a better parameter for reflecting heavy metal inhibition of activated sludge than INT-electron transport system activity. The ranking of tested heavy metals in order of decreasing toxicity based on TTC test was Hg2+, Cd2+, Cu2+, Ag+, Zn2+, Ni2+ and Pb2+, and the ranking based on INT test was Hg2+, Ag+, Cu2+, Cd2+, Zn2+, Ni2+ and Pb2+.

Bacteria↗

PubMed2004

Effects of the silanized mica surface on protein crystallization.

A freshly cleaved mica surface silanized by 3-aminopropyl triethoxysilane is flat over a large area, displays a controlled degree of hydrophobicity and contains positive charges. In this paper, mica sheets silanized by this method have been used as crystallization surfaces for lysozyme, trichosanthin and three other proteins of unknown structure. Crystallization experiments have been carried out by the hanging-drop vapour-diffusion technique and the results indicate that the silanized mica surface can ameliorate the protein crystallization process considerably compared with a silanized glass cover slip control. For lysozyme on the silanized mica surface, the induction time required for crystal growth decreases markedly. For trichosanthin, the crystal size is obviously larger and the number of crystals grown is much lower. For the three proteins of unknown structure, the diffraction ability of the crystals is improved considerably.

Aluminum Silicates↗

PubMed2004

Angular distributions for (3,4)(Lambda)H bound states in the (3,4)He(e,e(')K+) reaction.

The (3,4)(Lambda)H and (4)(Lambda)H hypernuclear bound states have been observed for the first time in kaon electroproduction on (3,4)He targets. The production cross sections have been determined at Q(2)=0.35 GeV2 and W=1.91 GeV. For either hypernucleus the nuclear form factor is determined by comparing the angular distribution of the (3,4)He(e,e(')K+)(3,4)(Lambda)H processes to the elementary cross section 1H(e,e K+)Lambda on the free proton, measured during the same experiment.

Journal Article↗

PubMed2004

Hypernuclear fine structure in (16)(Lambda)O and the LambdaN tensor interaction.

We have observed two gamma-ray transitions in (16)(Lambda)O from the 6.6 MeV excited 1(-)(2) state to both ground-state spin-doublet members (1(-)(1),0(-)) by the (K-,pi(-)gamma) reaction. We have obtained the ground-state doublet spacing to be 26.4+/-1.6(stat)+/-0.5(syst) keV and the excitation energy of the 1(-)(2) state to be 6561.7+/-1.1(stat)+/-1.7(syst) keV. The ground-state doublet spacing provides a small but nonzero strength of the tensor interaction between a Lambda and a nucleon. This is the first experimental result on the LambdaN tensor interaction.

Journal Article↗

PubMed2004

Correlated strength in the nuclear spectral function.

We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment locates by direct measurement the correlated strength predicted by theory.

Journal Article↗

PubMed2004

Nanoporous aluminum oxide affects neutrophil behaviour.

This study evaluates neutrophil responses on aluminum oxide membranes. Using an in vitro cell culture system, we have found that the pore size (20 and 200 nm in diameter) of alumina membranes have a significant effect on leukocyte morphology and activation. Specifically, our results show that 20-nm pore-size membranes were more potent in triggering PMN spreading and extending of pseudopodia than 200-nm pore-size membranes. The morphological changes are also associated with cell activation. In fact, adherent neutrophils on 20-nm pore-size membranes elicit much stronger initial oxygen free radical production. Overall, our results point out that membrane pore size significantly affects the extent of cellular responses of adherent neutrophils.

Aluminum Oxide↗

PubMed2004

Measurement of the electric form factor of the neutron at Q2=0.5 and 1.0 GeV2/c2.

The electric form factor of the neutron was determined from measurements of the d-->(e-->,e'n)p reaction for quasielastic kinematics. Polarized electrons were scattered off a polarized deuterated ammonia (15ND3) target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. We find G(n)(E)=0.0526+/-0.0033(stat)+/-0.0026(sys) and 0.0454+/-0.0054+/-0.0037 at Q(2)=0.5 and 1.0 (GeV/c)(2), respectively.

Journal Article↗

PubMed2004

Study on the ecological distribution of alveolar Echinococcus in Hulunbeier Pasture of Inner Mongolia, China.

A study on the ecological distribution of alveolar Echinococcus was carried out in the Hulunbeier Pasture of Inner Mongolia, China during 1998 and 1999. Animals examined included wolves (Canis lupus), red foxes (Vulpes vulpes), sand foxes (Vulpes corsac), domestic dogs (Canis familiaris), Microtus brandti, Meriones unguiculatus, Citellus dauricus, Allactaga sibirica, Phodopus sungorus and Ochotona daurica. Three wolves were found to be infected with E. granulosus. Two sand foxes were infected with E. multilocularis. The majority of infections of alveolar echinococcus was found in M. brandti. Based on the structure of metacestodes found in the livers of naturally infected M. brandti, 3 main variants were observed. Type I had small alveolar cysts with thin cyst walls. Type II had a larger cyst with a thick cyst wall. Infection of laboratory mice with the gravid segments isolated from the naturally infected sand foxes led to the formation of mature Type I alveolar metacestodes in the lungs and Type II metacestodes in the livers of infected animals, respectively.

Animals↗

PubMed2004

Augmentation of leptin and hypoxia-inducible factor 1alpha mRNAs in the pre-eclamptic placenta.

The placenta is a major source of leptin in the fetomaternal circulation, although its physiological role remains to be clarified. Leptin in the fetomaternal circulation is proposed to be a marker of acute stress in the fetus, and the fetus suffering from pre-eclampsia would be under chronic stress. In 16 pre-eclamptic placentas, the expressions of leptin, hypoxia-inducible factor 1alpha (HIF1alpha) and leptin receptor mRNAs were analyzed by semi-quantitative reverse-transcriptase-polymerase chain reaction and compared with clinical data. The co-expressions of leptin and the isoforms of the leptin receptor were observed in all the pre-eclamptic placentas. Leptin mRNA was significantly augmented in the pre-eclamptic placentas, although the level in fetal plasma was not high. The level of the expression of leptin mRNA was correlated with the placental HIF1alpha mRNA level and fetal body weight, but not with the levels of the leptin receptor isoforms in the pre-eclamptic placentas. This observation may suggest that autocrine/paracrine regulation of leptin exists in the human placenta and is upregulated in the pre-eclamptic placenta.

Adult↗

PubMed2004

Patterns of inflammation in mucosal biopsies of ulcerative colitis: perceived differences in pediatric populations are limited to children younger than 10 years.

The histologic criteria used to diagnose ulcerative colitis in colonic mucosal biopsies have been established for many years and include crypt architectural distortion, plasmacellular infiltrates, and neutrophils in the crypt epithelium and lumen. In several recent studies, it has been noted that colonic mucosal biopsies from children presenting with ulcerative colitis show fewer histologic abnormalities at initial presentation, especially less architectural distortion, than do biopsies from adults. In this study, colonic mucosal biopsies taken at the time of presentation of ulcerative colitis in 15 adults and 25 children were examined blindly by two pathologists. All biopsies were taken prior to the initiation of therapy. Twelve children were between 1 and 10 years of age, and 13 children were between the ages of 11 and 17 years. All patients had at least 1 year of follow-up, with clinical and pathologic confirmation of the diagnosis of ulcerative colitis. Five separate histologic features that are characteristic of ulcerative colitis were scored on mucosal biopsies. Children < or = 10 years of age had significantly less crypt branching, plasma cells in the lamina propria, cryptitis, crypt abscesses, and epithelial injury than adults (P values ranging from < 0.0001 to 0.0032). Children between the ages of 11 and 17 years had less cryptitis, crypt abscesses, and epithelial injury than adults (P values ranging from 0.0001 to 0.007) but similar degrees of crypt architectural distortion and plasma cell infiltrates. For all histologic features examined except epithelial injury, the significant findings were due to differences in biopsies taken proximal to the rectum. No significant differences in histology scores were found in rectal biopsies between any age group, except for epithelial injury, which was significantly less in children < or = 10 years. The findings show for the first time that the perceived differences between adults and children with ulcerative colitis are largely due to a decrease in histologic features of colitis in children less than 10 years of age. As children approach adulthood, the degree of inflammation and architectural distortion seen is similar to that found in adults. However, rectal biopsies show similar degrees of colitis in all age groups.

Adolescent↗

PubMed2004

Restoration of hair growth in mice with an alopecia areata-like disease using topical anthralin.

Anthralin is a widely used topical anti-psoriatic drug that may have an immunomodulating effect on alopecia areata (AA) as it does in psoriasis. The aims of the present study were to investigate the effects of anthralin on hair growth in balding C3H/HeJ mice affected by an AA-like disease and to study the underlying mechanisms. Affected C3H/HeJ mice were treated daily for 10 weeks on half of the dorsal skin with 0.2% anthralin and the contra-lateral side was treated with the vehicle ointment. The percentage of surface hair coverage and hair density was graded weekly for both sides and hair growth indices were calculated using these two variables. Hair regrowth was observed in 9/14 mice on the treated sides. Four mice displayed near complete replacement of normal density and length hairs. All the vehicle-treated sides showed either no change or continued hair loss. An RNase protection assay (RPA) showed that expression of tumor necrosis factor-alpha (TNF-alpha) and -beta were inhibited by anthralin upon successful treatment. It appears that anthralin may be an effective therapy for C3H/HeJ mice with AA and certain cytokines may be involved in the therapeutic effects of anthralin on restoring hair regrowth in AA-affected C3H/HeJ mice.

Administration, Topical↗

PubMed2004

A central role for plasminogen in the inflammatory response to biomaterials.

The inflammatory response to implanted biomaterials severely limits their deployment in patients. Plasminogen has been shown to play a central role in cell migration, and therefore could regulate this inflammatory response. We sought to determine if plasminogen influences recruitment of inflammatory cells to a biomaterial implanted into plasminogen-deficient (Plg(-/-)) mice. Small disks of polyethylene terephthalate, a material used in vascular grafts, were surgically implanted into the peritoneum of wild-type and Plg(-/-) mice. Recruitment of neutrophils and monocytes/macrophages into the peritoneum and onto the disks was measured, primarily at 18 h. Monocyte/macrophage recruitment was markedly blunted in Plg(-/-) mice compared with wild-type mice. Unexpectedly, neutrophil recruitment was also markedly decreased in the Plg(-/-) mice. While recruitment of leukocytes into the peritoneum was plasminogen-dependent, the adhesion of the emigrating cells to the implants was not. In contrast, adhesion but not recruitment was reduced in fibrinogen-deficient mice. Reconstitution of Plg(-/-) mice with intravenous or intraperitoneal plasminogen differentially restored monocyte/macrophage and neutrophil recruitment. Tranexamic acid, an inhibitor of the lysine binding sites of plasminogen, suppressed leukocyte recruitment in wild-type mice, but aprotinin, a plasmin inhibitor, did not. Plasminogen exerts a marked influence on both neutrophil and monocyte/macrophage recruitment to implanted biomaterials. This role is distinct from that of fibrinogen, and the two inflammatory cell types use plasminogen in different ways. Plasminogen represents a therapeutic target for controlling the inflammatory response to implanted materials.

Animals↗