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PubMed2004

Diode laser-activated bleaching.

This study describes a preclinical investigation with laser-activated bleaching agent for discolored teeth. Bleaching techniques involve a broad-spectrum approach utilizing hydrogen peroxide (3-38%) with or without heat or laser, carbamide peroxide (10-30%), or a mixture of sodium perborate and hydrogen peroxide. Extracted human maxillary central incisors were selected. In the bleaching experiment, 38% hydrogen peroxide was used. Two different laser systems and light emission diodes for activation of the bleaching agent were used: diode laser, wavelength 970 nm, and infra-red diode laser, wavelength 790 nm, with eight blue light emission diodes, wavelength 467 nm. The enamel surface was evaluated with the scanning electron microscope. The method of chemical oxidation resulted in a 2-3 shade change in one treatment (15 min). Shorter time (5 min) was not effective. The diode laser, wavelength 970 nm, and the bleaching agent produced the same effect but with a shorter time of bleaching process (5 min - 1 W, 2.5 min - 2 W). Infra-red diode laser, wavelength 790 nm with eight blue light emission diodes, wavelength 467 nm, and the bleaching agent reached the desired color shade also after a shorter time (5 min - 40 mW). Slight surface modification after the bleaching process was detected with scanning electron microscopy. Currently, the laser has been proven the most valuable energy source for power bleaching with simple and short application in the dental office.

Hydrogen Peroxide↗

PubMed2005

[Role of pre-coating in artificial vessel endothelialization].

OBJECTIVE: To understand the value of pre-coating in artificial vessel endothelialization. METHODS: Literature concerning pre-coating in artificial vessel endothelialization was extensively reviewed. RESULTS: Pre-coating included chemical coatings (collagen, fibronectin, laminin, poly-l-lysin, gelatin and extracellular matrix), pre-clotting (plasma, blood, serum and fibrin glue), chemical bonding (heparin, RGD and lectins) and surface modification. Most of them could enhance the adhesion of the endothelial cells. CONCLUSION: Pre-coating could improve endothelialization, but further research is needed to search for the appropriate concentration and incubation time.

Animals↗

PubMed2004

[Oriented immobilization of human IgG by protein A on imaging ellipsometry biosensor].

The biosensor based on optical imaging ellipsometry, can be used to detect directly, without labeling, the surface concentration of biomolecules on solid surface. The feasibility of using protein A to immobilize antibody on the silicon surface of the imaging ellipsometry biosensor was investigated in this study. The results showed that the anti-IgG immobilized by the protein A on silicon surface could bind effectively human IgG, and the human IgG immobilized on silicon surface by protein A bound more polyclonal antibody molecules than that immobilized on silicon surface directly, suggesting that protein A might block the surface to prevent the absorption of human IgG on surface directly, which might compromise its native configuration. The silicon surface modified with protein A is expected to be used to immobilize a variety of antibodies, as protein A can bind selectively the Fc regions of many mammalian IgG. The combination of imaging ellipsometry and the protein A surface modification has the potential to be developed into immunoassays of high sensitivity.

Biosensing Techniques↗

PubMed2005

[Photocatalytic removing of a mustard gas analogue 2-CEES vapor over SO4(2-)/TiO2].

Disinfection with photocatalysis, compared to with the conventional cleanout, is both high efficient and non contaminative, but the simple TiO2 photocatalyst is showing to be of low activity and low active stability so to be hardly practical application. In the paper, SO4(2-)/TiO2 were papered by surface modification of TiO2 with dilute H2SO4, and the photocatalytic degradation of 2-chloroethyl ethyl sulfide (2-CEES) on the samples was examined in a fixed-bed microreactor. The examination show that the acidic modification enhanced both the activity and the active stability of TiO2, and the sample ST200 prepared by calcination at 200 degrees C was better than ST400 by calcination at 400 degrees C. The effect of water vapor content and reaction temperature on the photocatalytic degradation of 2-CEES was also tested, showing that the sample ST200 had high activity and stability at 90 degrees C, and kept a constant activity when adding 30.5 mL/L water vapor into the reactive system in which 2-CEES initial concentration was low to < 61 microL x L(-1). In addition, it was found that supporting SO4(2-)/TiO2 on gamma-Al2O3, SiO2 and active carbon could improve on the activity and stability of SO4(2-)/TiO2, and on supports SiO2 is the best one.

Air Pollutants↗

PubMed2005

[Laboratory on a microfluidic chip].

The recent achievements of microfluidic chip and its applications, based on the works mainly carried out in the authors' lab are reviewed. The chip fabrication capabilities have been extended into design and fabricate chips with higher degree of complexity in different materials, such as quartz, glass, polymethyl methacrylate (PMMA), and polydimethyl siloxane (PDMS). A set of methods for surface modification of micro-channels on such materials have been developed, which results in better reproducibility and higher efficiency in protein and peptide analysis. The use of novel materials for chip fabrication is also under investigation. A series of microfluidic workstations with integrated chip manipulation as well as laser induced fluorescence (LIF), ultraviolet (UV), electrochemical and chemiluminescence detection modules have been developed to attain the abilities of complex microfluidic control and data acquisition schemes. A single cell/single molecule imagining system was built up for dynamic analysis of molecular or cellular events too. Based on the work mentioned above, different functional units, such as membrane, monolithic, isotachophoresis (ITP) etc were set up and integrated. Glycoform separation of turkey ovalbumin in a lectin monolithic column and an electrophoresis channel was performed on an integrated microchip. And a novel technique has been developed that allows for the coupling of ITP and non-gel sieving electrophoresis for protein analysis in a single microchip and resulting in - 50 fold increase of the sensitivity in comparison with the use of gel electrophoresis only. A single molecule detection (SMD) based technique was developed for simultaneously measuring both bulk flow and near-wall flow velocity in the microchannels. And more recently, an SMD based technology was developed for observing molecular interactions at single molecule level. An ultra-rapid microchip electrophoresis method was established for simultaneous determination intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) related to apoptosis and oxidative stress. In an effort to develop a novel microfluidic based drug screening platform, systematic studies on the interaction between granulocyte colony-stimulating factor (G-CSF) and sulfated oligosaccharides were carried out at both molecular and cellular levels. Doxorubicin induced apoptosis of human hepatocellular carcinoma (HepG2) was studied using the integrated microfluidic device with concentration generator. In the application phase, severe acute respiratory syndrome (SARS) diagnosis based on reverse transcription-polymerase chain reaction (RT-PCR) and microfluidic chip electrophoresis (MCE) with 18 cases, methylation analysis of the P16 gene in 159 samples of patients and references for cancer diagnosis and polymorphism analysis of angiotenigen gene in 226 patients and references with essential hypertension are described. Forty-three up to date references are

Animals↗

PubMed2006

[Research and development of biomedical application of carbon nanotubes and related composites].

Carbon nanotubes, a new member of the carbon material family, can be considered as graphite sheets rolled-up into cylinders with diameters ranging in the nanometer scale. In recent years, carbon nanotubes have attracted intensive interests because of their unique nanostructures and outstanding mechanical, electrical and magnetic properties. In this paper, the structures and basic features of carbon nanotubes were described in brief. The research advances in the carbon nanotubes on the specific recognition of biomolecules by surface modification and functionalization, in the enhancement to cell growth as culture scaffolds in vitro, and in the improvement of biocompatibility for implantable biomedical material were reviewed. Also comments were made on their potential applications in biomedical sensor and biomedical microelectrics.

Biocompatible Materials↗

PubMed2006

Microfluidic enzyme-linked immunosorbent assay technology.

In this chapter, we have presented an overview of microfluidic enzyme-linked immunosorbent assay (ELISA) by first introducing the principle of immunoassay, ELISA, and microfabricated devices, followed by a discussion of microfabrication technology and the characterization of microfluidic components. Significant advances in laboratory technology are contributing to the further understanding of microfluidic function, surface modification and immobilization, which lead to the development of improved biomolecule detection methods and prospective applications. For the future, the exploitation of more robust-manufacturing processes and integrated assay systems in an automatic fashion with much reduced assay time and reagent consumption will allow for the effective detection and quantification of biological agents that are of interest in medical diagnostics, food safety surveillance, and environmental monitoring.

Enzyme-Linked Immunosorbent Assay↗

PubMed1991

Filtration of platelet concentrates.

The transfusion of leukocyte-containing blood products causes a number of side reactions, which among others induces alterations of the immune system of the recipient leading to alloimmunization or immunosuppression. Antibodies against antigenic determinants of the major histocompatibility complex-proteins of class I are the major cause of alloimmunization. Though platelets are easy targets for HLA antibodies, they cannot induce the antibody production themselves. This requires leukocytes, carrying the MHC-proteins of the class II. Standard platelet concentrates for the clinical routine have more than 10(6) leukocytes. Leukocyte filters with a special surface modification reduce the number of leukocytes in platelet concentrates underneath this CILL-value (critical immunogenic load of leukocytes), thus reducing the antigenic, immunogenic effects of leukocyte contamination considerably.

Blood Component Transfusion↗

PubMed1990

Osseointegration of titanium implants in total hip arthroplasty.

Osseointegration is defined as direct contact on the light microscopic level between living bone tissue and the implant. Using titanium screw dental implants in the jaw, a lasting interface under loaded conditions extending over a 20-year follow-up period has been demonstrated. This demonstration brings up the question whether a similar interface can be achieved in total hip arthroplasty (THA) between living bone and a titanium alloy implant under necessitated conditions of immediate loading. Two series of cases are reported. The first series used a femoral, press-fit, titanium alloy component and the second used a press-fit titanium acetabular component and redesigned femoral, press-fit, titanium alloy component. Both demonstrated a high percentage of good to excellent results. Roentgenograms showed that the geometrical changes in the redesigned femoral component gave early indications of a better fixation with loading in valgus, less subsidence, and less evidence of distal stress transfer. A two-and-one-half-year postoperative anatomic specimen study confirmed osseointegration to the press-fit titanium alloy femoral component. Multiple areas of contact between bone and metal without fibrous interposition were seen. Examination by electron microscopy supported the light microscopic findings. These findings support further use of smooth, press-fit titanium components in THAs without the need for porous coating, mesh, or other surface modifications.

Adult↗

PubMed1990

Auger and pixe microanalysis of intrauterine devices (IUDs).

Auger Emission Spectroscopy (AES) and Particle Induced X-ray Emission (PIXE) analysis were employed in a study on the calcification and oxidation processes of the copper wires used in Intra-Uterine Device (IUDs) contraceptives. A strong copper release (approximately 50 micrograms/day) has been observed in the first year of IUDS application during the high device antifertility effect. The copper release is reduced with the IUD-use time, because of the calcification process on the surface by organic liquids. This effect produces a drastic reduction in the contraceptive efficiency, and a new IUDs replacement is needed after about 2 years of use. Auger, X-ray spectrometry and scanning electron microscopy (SEM) have been used to investigate the lifetime and efficiency of IUDS in order to understand the surface modification of copper wire during its permanence in the intrauterine environment.

Calcium↗

PubMedDate not supplied

Morphological changes induced by epidermal growth factor and estradiol on CG5 human breast cancer cell line: a scanning electron microscopy study.

We studied the morphological changes induced by 17-b-estradiol (E2) and/or Epidermal Growth Factor (EGF) in an estrogen sensitive human breast cancer cell line (CG5) characterized by a high growth responsiveness to EGF and by a single class of high affinity I-125 EGF binding sites. EGF treated cultures showed conspicuous morphological changes consisting of retraction from the substrate, loss of cell-to-cell contacts and expression of surface crest-like and bled protrusions. E2-treated cells showed an increased number of microvilli with respect to control. In cells simultaneously treated with EGF and E2, despite the expression of microvilli, cell surface modifications were similar to those found in the presence of EGF alone, suggesting that EGF may negatively modulate the estrogen-induced morphological changes. In CG5 cells EGF induced a reduction of ER and PR levels and inhibited the estrogen-induced increase of PR. Our findings suggest that the activation of specific EGF-induced intracellular pathways could decrease or modulate those induced by E2.

Breast Neoplasms↗

PubMed1987

The design of cytotoxic-agent-antibody conjugates.

The rationale for the use of antibodies as carriers of cancer chemotherapeutic agents is based upon: the presence on cells of tumor-associated cell surface antigens (TAA); the ability to obtain specific polyclonal or monoclonal antibodies against them; and the availability of methods for binding appropriate toxic agents or radionuclides with retention of activity of both antibody and agents. The general finding so far has been that both conventional polyclonal and hybridoma-derived monoclonal antibodies can deliver cytocidal amounts of toxic agents to target tumor cells both in vitro and in vivo. Moreover, various agents with different modes of antitumor activity (e.g., DNA intercalation or alkylation, enzyme inhibition, and cell surface modification) have all produced superior tumor inhibition in conjugate form compared to the individual or synergistic inhibition produced by agent and antibody. Recent studies are contributing to the understanding of the mechanism of action of drug-antibody conjugates and are thus establishing guidelines for this approach to cancer therapy.

Antibiotics, Antineoplastic↗

PubMed1989

[New materials for intraocular lenses].

The first intraocular lens implanted in a human eye 39 years then lenses ago, was made of polymethylmethacrylate (PMMA). Today this material is considered to be the standard, so every new type of material is compared to PMMA and must fulfil the requirements demanded of an intraocular implant today. Therefore, every attempt is made to use PMMA as the main structure while eliminating the disadvantageous characteristics even though they are minimal. Thus, the hydrophobic surface can be made more biocompatible by heparin-surface modification. In recent years, hydroxyethylmethacrylate (HEMA) and silicone have achieved a certain level of clinical importance. Another of the new materials is polycarbonate, which is still in the preclinical phase.

Benzhydryl Compounds↗

PubMedDate not supplied

[In vitro effect of an air-powder abrasive system on the susceptibility of dental tissues to artificial caries].

An air-powder jet abrasive system has recently been introduced for stain removal from teeth. The purpose of this study was to investigate whether its abrasive effect on enamel and on the root renders these surfaces more caries prone. The AIR-FLOW (EMS SA) abrasive was directed for 30 seconds on predetermined (test) sites of the crown and the root of each of 10 teeth, under controlled conditions. These and adjacent (control) sites in the form of windows, were then exposed to an acid gel for caries-like lesion formation. The central sections of each window were examined under the polarizing microscope. The enamel treated with the abrasive appeared somewhat roughened while the root showed crater-like abrasion defects averaging 303 mm (+/- 140) in depth. The mean depth of enamel test lesions was 253 mm (+/- 77) and that of control lesions 98 mm (+/- 77), the difference being statistically significant (p less than 0.001). The corresponding values for the root lesions were 695 mm (+/- 103) and 695 mm (+/- 120) respectively. Consequently, enamel surface modification by AIR-FLOW decreased the resistance of enamel to caries-like lesions in vitro and it is postulated that this may also happen at "susceptible sites" in vivo. Loss of cementum and superficial dentine abraded by AIR-FLOW was significant but did not lead to increased root susceptibility to caries-like lesions in vitro.

Air↗

PubMed1988

Growth control of human foreskin fibroblasts and inhibition of extracellular sialidase activity by 2-deoxy-2,3-dehydro-N-acetylneuraminic acid.

Normal human fibroblasts have two extreme modes of existence in culture, quiescent and proliferative. The growth and division of these cells are usually well regulated by the action of various endogenously generated stimulators and inhibitors. We have speculated that an extracellular sialidase may be involved in the regulation of growth and that inhibition of this activity might decrease or abolish cell growth. To test this hypothesis, we have incubated preconfluent cultures of fibroblasts in the presence and absence of a potent sialidase inhibitor, 2-deoxy-2,3-dehydro-N-acetylneuraminic acid. Treatment of cells with this inhibitor resulted in the inhibition of an extracellular sialidase activity for up to 24 h and had a marked growth inhibitory effect in a concentration-dependent manner. The effect of the inhibitor on cell proliferation was specific and reversible. During a chase period of 48 h after pulse labeling cells with [3H]N-acetylmannosamine and [14C]serine, there was a 15% decrease of [3H]sialic acid in the membrane-bound GM3 with 80 microM inhibitor in the medium, as compared with a 32% decrease in the controls. Our results suggest that an extracellular sialidase may participate in cell-surface modifications that accompany (or control) the changes observed when cells traverse the cell cycle, from the quiescent to the proliferative phase.

Cell Division↗

PubMed1986

Corrosion and ion transfer from porous metallic alloys to tissues.

Investigations on porous and nonporous alloys currently available for surgical implant device stabilization through tissue ingrowth have shown microstructures that are characteristic of the thermal processing history of the device and alloy with differences between the nonporous and porous devices of the same nominal chemical analysis, in vitro corrosion potentials that are similar for porous and nonporous alloys and corrosion rates that are approximately proportional to the increases in relative surface areas (X 2 to X 10); local tissue interactions at the cellular level that are specific to the type and amount of elemental constituents present at the interface; and no direct correlations between the local cellular responses (fibroblasts) and the potential for hypersensitivity and other systemically mediated responses. Evaluations of the available published literature and available information on device retrievals and analyses support the opinion that no quantitative, statistically based epidemiologic studies have yet established significant correlations between selected metallic ions and major types of tissue lesions. However, with the changes in surface area and basic surface chemistry for existing alloy systems, research on the long-term tissue responses should be emphasized. In our opinion, biomaterial surface modifications are possible, whereby the relative quantities of released ions available to the environment could be significantly reduced.

Alloys↗

PubMed1986

[Current status and future perspectives of extracorporeal blood purification].

After the description of the main indications for an extracorporeal blood purification the authors enter the at present existing and applied detoxication methods on the basis of membranes and absorbents, respectively. A short characterization of the most important membrane separation techniques peritoneal dialysis, haemodialysis, haemofiltration, haemodiafiltration and membrane plasma separation, respectively, is given. Moreover, an estimation of the cascade methods is given, i.e. the application of several separation filters. As adsorptive methods the haemoperfusion and the plasma perfusion, respectively, are assessed with their advantages and disadvantages and the authors enter the possibility of the combination of the procedures mentioned. As problems which are to be solved still in the first place the deficient blood compatibility, selectivity, individualization and continuity are discussed and ways of solution are shown which up to now are entered upon for the improvement and optimization, respectively, of the problems mentioned. In this case particularly the surface modification of materials and the search for new materials, respectively, as well as the use of special models is emphasized as important for future. In the field of selectivity adsorptive methods are to be developed in the first place which without danger of complications remove relevant metabolites from the organism. For the future is above all to be reckoned with the further development of so-called hybrid organs, since such organs may best repeat biological processes.

Acute Kidney Injury↗

PubMed1986

[Role of splenectomy in impairing lymphocyte elimination in patients with lymphogranulomatosis].

The study group included 113 patients in a continuing 1 to 10 year-long complete clinical-hematological remission from Hodgkin's disease. 43 of them had prior splenectomy. The latter revealed a higher level of lymphocytes (chiefly 0-cells) and a diminished response of mononuclear blood cells to PHA as compared to the other patients and healthy controls. Also, they had more lymphocytes which became capable of E-rosette formation following a short-term incubation at 37 degrees C (lymphocyte reactivation by means of surface modification). The negative correlation between the reactivated T-cells level and mononuclear cell response to PHA suggested a functional blocking of T-cells involving damage to membranes. The absence of reactivated T-lymphocytes in nonsplenectomized patients was regarded as circumstantial evidence for the role played by the spleen in withdrawing faulty lymphocytes from peripheral blood.

Hodgkin Disease↗