Who is who in oral cancer?

Great attention has been attached to explore the association between oral bacteria and oral cancer. Recently, four common inhabitants of oral cavity, Porphyromonas gingivalis, Fusobacterium nucleatum, Treponema denticola and Streptococcus anginosus, have been identified as potential etiologic bacterial agents for oral carcinogenesis. They might promote the oncogenesis and progression of oral cancer by induction of chronic inflammation, enhancement of migration and invasiveness, inhibition of cell apoptosis, augment of cell proliferation, suppression of immune system and production of carcinogenic substances. Thus, this review will focus on the possible mechanisms of these oral bacteria contributing to occurrence and development of oral cancer, and the potential clinical implications of utilizing oral bacteria on the diagnosis, prevention and treatment of oral cancer will be discussed.

Glucosamine oral administration as an adjunct to hyaluronic acid injection in treating temporomandibular joint osteoarthritis.

OBJECTIVE: To investigate the therapeutic effect of oral glucosamine (GS) as an adjunct to hyaluronic acid (HA) injection on patients with temporomandibular joint osteoarthritis (TMJ OA). METHODS: In this clinical trial, 136 participants, diagnosed as TMJ OA clinically and radiographically, were enrolled and randomized into two groups (group GS + HA: oral GS + HA injection; group placebo + HA: oral placebo + HA injection). Pain, maximum interincisal mouth opening (MMO), the levels of IL-1ß, IL-6, and TGF-ß in TMJ synovial were defined as the outcome measurements and conducted before operation, and at 1-month and 1-year follow-up. RESULTS: In both groups, pain scores were decreased and MMOs were increased at 1-month and 1-year follow-up, the changes at 1-year follow-up showed statistically significant intergroup differences. At 1-month follow-up, only IL-6 concentration was lower in group GS + HA than that in group placebo + HA. One year later, TGF-ß concentration was higher and IL-6 and IL-1ß concentrations were lower in group GS + HA than those in group placebo + HA. CONCLUSIONS: Both strategies alleviated symptoms in short term, but the patients treated with GS benefited more than those with placebo in long term, which may be due to the suppression of IL-1ß and IL-6 and the stimulation of TGF-ß.

Is There a Difference in Intra-Articular Injections of Corticosteroids, Hyaluronate, or Placebo for Temporomandibular Osteoarthritis?

PURPOSE: Corticosteroids are widely used for treatment of temporomandibular joint (TMJ) osteoarthritis (OA). This study investigated the effects of corticosteroids on TMJOA compared with placebo or hyaluronate. MATERIALS AND METHODS: The authors designed and implemented a systematic review and meta-analysis to compare the effects of intra-articular injection of corticosteroid, hyaluronate, or placebo for patients with TMJOA. The authors searched related randomized controlled studies electronically in multiple English- and Chinese-language electronic databases. The predictor variable was intra-articular injection with corticosteroid, hyaluronate, or placebo. Primary outcome variables were pain intensity and maximal mouth opening. Other variables included success rate and adverse events. Meta-analyses were performed with Rev Man 5.3. RESULTS: Eight studies met the inclusion criteria. Meta-analysis showed that corticosteroid injections after arthrocentesis were superior to placebo in relieving pain as assessed with the visual analog scale (mean difference [MD], -0.74; 95% confidence interval [CI], -1.34 to -0.13; P = .02; I2 = 0%) in the long-term, but was inferior in increasing maximal mouth opening (MD, -2.06; 95% CI, -2.76 to -1.36; P < .00001; I2 = 28%). Although corticosteroid and hyaluronate injections without arthrocentesis decreased pain and improved maximal mouth opening, the corticosteroid group had a significantly lower success rate (odds ratio = 0.41; 95% CI, 0.17-1.00; P = .05; I2 = 0%) than the hyaluronate group in the short term. CONCLUSION: Corticosteroid injections after arthrocentesis are recommended for patients with TMJOA to relieve joint pain rather than increase maximal mouth opening. Corticosteroid and hyaluronate have marked effectiveness on TMJOA; however, hyaluronate might be the better alternative to some extent.

Synthesis of Hemoglobin Conjugated Polymeric Micelle: A ZnPc Carrier with Oxygen Self-Compensating Ability for Photodynamic Therapy.

Photodynamic therapy (PDT) is a promising singlet oxygen ((1)O2) mediated clinical treatment for many tumors. As the source of (1)O2, oxygen plays an important role in the curative effect of PDT. However, the facts of photochemical depletion of oxygen and the intrinsic hypoxic microenvironment of tumors remain the major challenges. In this work, a novel photosensitizer carrier with oxygen self-compensating ability was designed for PDT. It was synthesized via chemical conjugation of hemoglobin (Hb) to polymeric micelles formed by triblock copolymers of poly(ethylene glycol)-block-poly(acrylic acid)-block-polystyrene (PEG-b-PAA-b-PS). The PEG-b-PAA-b-PS and resultant micelles in aqueous solution were comprehensively characterized by means of FTIR, (1)H NMR, GPC, DLS, TEM, and fluorescence spectroscopy. The oxygen-binding capacity and antioxidative activity of the Hb conjugated micelles were evaluated via UV-vis spectroscopy. In addition, compared with the control micelles without Hb, the Hb conjugated photosensitizer carrier was able to generate more (1)O2 and exert greater photocytotoxicity on Hela cells in vitro.

Ssc-miR-7139-3p suppresses foot-and-mouth disease virus replication by promoting degradation of 3Cpro through targeting apoptosis-negative regulatory gene Bcl-2.

Foot-and-mouth disease is a highly contagious and infectious disease affecting cloven-hoofed animals. Disease control is complicated by its highly contagious nature and antigenic diversity. Host microRNAs (miRNAs) are post-transcriptional regulators that either promote or repress viral replications in virus infection. In the present study, we found that ssc-miR-7139-3p (Sus scrofa miR-7139-3p) was significantly up-regulated in host cells during foot-and-mouth disease virus (FMDV) infection. Overexpression of miR-7139-3p attenuated FMDV replication, whereas inhibition promoted FMDV replication. In addition, the survival rate of FMDV infected suckling mice was increased through injection of miR-7139-3p agomiR. Further studies revealed that miR-7139-3p targets Bcl-2 to initiate the apoptotic pathway and caspase-3 cleaved 3Cpro behind the 174th aspartic acid (D174), which eventually promotes the degradation of 3Cpro. Overall, our findings demonstrate that miR-7139-3p suppresses FMDV replication by promoting degradation of 3Cpro through targeting the apoptosis-negative regulatory gene Bcl-2.

A digital intervention using virtual reality helmets to reduce dental anxiety of children under local anesthesia and primary teeth extraction: A randomized clinical trial.

INTRODUCTION: Behavior management of children during dental treatment is an important but challenging issue. As a new technique, VR has been applied in pediatric dental anxiety. But there is no final conclusion whether VR reduces children's dental anxiety. METHODS: The aim of the study is to assess the effectiveness of a digital intervention using virtual reality (VR) helmets on dental anxiety, pain perception, and behavior triggered for children, as well as occurrence of simulator sickness in local anesthesia and primary teeth extraction. A total of 128 children, who needed primary teeth extraction under local anesthesia, were randomly allocated into two groups: use VR helmets and traditional behavior guidance procedures (control). Modified Child Fear Survey Schedule Dental Subscale (CFSS-DS), Wong-Baker FACES Pain Scale, Houpt Scale, and Simulator sickness questionnaire (SSQ) were used to assess children's dental anxiety, pain perception, and behavior triggered and occurrence of simulator sickness. RESULTS: CFSS-DS score in the VR group was significantly decreased after dental treatment (34.58±6.90 before operation and 32.32±15.58 after operation, p = .02). The score of Wong Baker Scale in the VR group (3.47±0.76) was significantly lower than that in the control group (5.56±1.13, p = .015). There was no significant difference in the Houpt Behavior Scale score and the SSQ score between the VR group and the control group (p = .35, p = .305). CONCLUSION: The use of VR helmets in primary teeth extraction can significantly reduce dental anxiety and pain perception in children without occurrence of simulator sickness.

Coxsackievirus A6 was the most common enterovirus serotype causing hand, foot, and mouth disease in Shiyan City, central China.

BACKGROUND: Hand, foot, and mouth disease (HFMD) has become one of the most common infectious diseases in China. Before 2016, the primary causal serotypes were enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). Following the introduction of EV-A71 vaccines in China since 2016, the situation could change. CV-A6 has recently replaced EV-A71 and CV-A16 in some areas of China. However, the epidemiological characteristics of central China remain unknown. AIM: To investigate the clinical symptoms and pathogen spectrum of HFMD in Shiyan City, central China, in recent years. METHODS: The epidemiological, clinical, and laboratory data from HFMD cases reported to the Shiyan Center for Disease Control and Prevention between January 2016 and December 2020 were analyzed. 196 throat swab specimens were collected from hospitalized HFMD patients between January 2018 and December 2020. To detect and genotype enteroviruses, real-time reverse transcription-polymerase chain reaction and sequencing of the 5'-untranslated region were used. In Shiyan, 168 laboratory-confirmed HFMD cases were studied using a logistic regression model to determine the effect of predominant enterovirus serotypes. Based on the logistic regression model, the least absolute shrinkage and selection operator model was used to analyze the correlation between CV-A6 infection and various clinical characteristics in HFMD patients in Shiyan. RESULTS: From 2016 to 2020, 35840 HFMD cases were reported in Shiyan. The number of cases decreased by 48.4% from 2016 to 2017. Approximately 1.58-fold increases were found in 2018 and 2019 when compared to the previous year, respectively. In 2020, a decrease of about 85.5% was reported when compared to 2019. The most common serotypes shifted from EV-A71 and CV-A16 (about 60%-80% in 2016 and 2018) to others (more than 80.0% in 2017, 2019, and 2020). EV-A71 lost its dominance in 2017 in Shiyan. Among 196 confirmed HFMD cases, 85.7% tested positive for enterovirus, with CV-A6 being the most common serotype (121/168, 72.0%). The positive rates for CV-A16 and CV-A10 were 4.8% and 3.0%, respectively. There was no EV-A71 discovered. Infection with CV-A6 was linked to fever, myocardial damage, increased creatine kinase MB isoenzyme, and lactate dehydrogenase levels. CONCLUSION: CV-A6 was the most common enterovirus serotype in Shiyan City, replacing EV-A71 and CV-A16 as the HFMD pathogen. Developing vaccines against CV-A6 or multiple pathogens, as well as rising CV-A6 surveillance, will help prevent HFMD in central China.

Conformational changes of protein adsorbed on tailored flat substrates with different chemistries.

Changes in the bioactivity of a protein after being adsorbed on a material surface may result from conformational changes of the protein. Unfortunately, however, direct evidence of such conformational changes of proteins adsorbed on a flat material surface is sparse so far. This is because probing the conformation of an adsorbed protein on material surfaces, especially flat ones, remains a challenge due to considerable experimental difficulties. In this study, the surface-enhanced Raman scattering (SERS) technique is used to characterize the conformational changes of a protein (lysozyme) adsorbed on tailored flat gold substrates with different chemistries. Two such substrates are formed by self-assembly of octadecanethiol and thiolated PEG on gold chips (Au-C18 and Au-PEG). Preliminary results reveal that, compared to the hydrophobic Au-C18 surface, the hydrophilic Au-PEG surface has much smaller effect on the conformation of lysozyme in aqueous solution, which thereby keeps its high bioactivity. The conformational changes of lysozyme adsorbed on material surfaces with different chemistries are well correlated with changes in its bioactivity.

Phenotype and molecular characterizations of a family with dentinogenesis imperfecta shields type II with a novel DSPP mutation.

BACKGROUND: Dentinogenesis imperfecta (DGI), Shields type-II is an autosomal dominant genetic disease which severely affects the function of the patients' teeth. The dentin sialophosphoprotein (DSPP) gene is considered to be the pathogenic gene of DGI-II. In this study, a DGI-II family with a novel DSPP mutation were collected, functional characteristics of DGI cells and clinical features were analyzed to better understand the genotype-phenotype relationship of this disease. METHODS: Clinical data were collected, whole exome sequencing (WES) was conducted, and Sanger sequencing was used to verify the mutation sites. Physical characteristics of the patient's teeth were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The localization of green fluorescent protein (GFP)-fused wild-type (WT) dentin sialoprotein (DSP) and its variant were evaluated via an immunocytochemistry (ICC) assay. The behaviors of human dental pulp stem cells (hDPSCs) were investigated by flow cytometry, osteogenic differentiation, and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: A novel heterozygous mutation c.53T > G (p. Val18Gly) in DSPP was found in this family. The SEM results showed that the participants' teeth had reduced and irregular dentinal tubes. The EDS results showed that the Ca/P ratio of the patients' teeth was significantly higher than that of the control group. The ICC assay showed that the mutant DSP was entrapped in the endoplasmic reticulum (ER), while the WT DSP located mainly in the Golgi apparatus. In comparison with normal cells, the patient's cells exhibited significantly decreased mineralization ability and lower expression levels of DSPP and RUNX2. CONCLUSIONS: The c.53T > G (p. Val18Gly) DSPP variant was shown to present with rare hypoplastic enamel defects. Functional analysis revealed that this novel variant disturbs dentinal characteristics and pulp cell behavior.

Near-Infrared Plasmon-Boosted Heat/Oxygen Enrichment for Reversing Rheumatoid Arthritis with Metal/Semiconductor Composites.

Rheumatoid arthritis (RA) is an autoimmune disease that often causes progressive joint dysfunction, even disability and death in severe cases. The radical improvement of inflammatory cell infiltration and the resulting disorder in oxygen supply is a novel therapeutic direction for RA. Herein, a near-infrared-absorbing metal/semiconductor composite, polyethylene glycol-modified ceria-shell-coated gold nanorod (Au@CeO2), is fabricated for topical photothermal/oxygen-enriched combination therapy for RA in a mouse model. Upon laser irradiation, the photothermal conversion of Au@CeO2 is exponentially enhanced by the localized surface plasma resonance-induced light focusing. The elevated temperature can not only remarkably obliterate hyperproliferative inflammatory cells gathered in diseased joints but also vastly increase the catalase-like activity of ceria to accelerate the decomposition of H2O2 to produce much oxygen, which relieves hypoxia. Significantly, RA-induced lesions are improved, and the expression of proinflammatory cytokines and hypoxia-inducible factors is effectively repressed under the cooperation of heat and oxygen. Overall, the core/shell-structured Au@CeO2 is a promising nanotherapeutic platform that can well realize light-driven heat/oxygen enrichment to completely cure RA from the perspective of pathogenesis.

Downregulation of miR-155-5p facilitates enterovirus 71 replication through suppression of type I IFN response by targeting FOXO3/IRF7 pathway.

Enterovirus 71 (EV71), the major cause of hand-foot-and-mouth disease (HFMD), has evolved diverse strategies to counter the type I interferon (IFN-I) response during infection. Recently, microRNAs have regulatory roles in host innate immune responses to viral infections; however, whether EV71 escapes the IFN-I antiviral response through regulation of miRNAs remains unclear. Using a microarray assay, microRNA-155-5p (miR-155-5p) was found to be significantly up-regulated in serum from patients with EV71 infection and the increased expression of miR-155-5p was further confirmed in vivo and in vitro in response to EV71 infection. miR-155-5p overexpression suppressed EV71 titers and VP1 protein level, while miR-155-5p inhibition had an opposite result. Moreover, we found that miR-155-5p overexpression enhanced EV71 triggered IFN I production and the expressions of IFN-stimulated genes (ISGs), while inhibition of miR-155-5p suppressed these processes. Furthermore, bioinformatics analysis and luciferase reporter assay demonstrated that miR-155-5p directly targeted forkhead box protein O3 (FOXO3) and negatively regulated FOXO3/IRF7 axis, an important regulatory pathway for type I IFN production during EV71 infection. Inhibition of FOXO3 reversed the effects of miR-155-5p inhibitor on EV71 replication and the type I IFN production. Importantly, in EV71 infection mice, agomir-155-5p injection resulted in a significant reduction of viral VP1 protein expressions in brain and lung tissues, increased IFN-α/ß production and increased mice survival rate. In contrast, antagomir-155-5p enhanced EV71 induced these effects. Collectively, our study indicates that weaken miR-155-5p facilitates EV71 replication through suppression of type I IFN response by FOXO3/IRF7 pathway, thereby suggesting a novel strategy for developing effective antiviral therapy.

[Effect of proliferation, c-met and vascular endothelial growth factor expression in the Eca109/9706 cells by liposomal quercetin].

OBJECTIVE: To explore the effect of cell proliferation, c-met and vascular endothelial growth factor (VEGF) expression by liposomal quercetin in the Eca109/9706 cells induced by liposomal quercetin. METHODS: The suppressing rate of cultured Eca109/9706 cells was detected by MTT assay. After 48-hour-exposure to liposomal quercetin, the expression and cellular localization of c-met and VEGF in Eca109/9706 cells were examined by using immunohistochemistry assay and Western blotting. RESULTS: The suppressing rate of Eca109/9706 cells was in the order of LQ2 group > LQ1 group > nLQ group > control group (P < 0.05). The protein expression of c-met and VEGF was found in Eca109/9706 cells cytoplasma as well as in nuclei by using immunohistochemistry assay. The Immuno-reaction intensity of c-met and VEGF was in the order of control group > nLQ group > LQ1 group > LQ2 group (P <0.05). The western blotting showed the intensity of immunoblotting signals for c-met-IR and VEGF-IR was in the order of control group > nLQ group > LQ1 group > LQ2 group (P < 0.05). CONCLUSION: The liposomal quercetin could suppress the proliferation of culture Eca109/9706 cells, which was about to be related with the suppression high expression of c-met and VEGF.

The maintenance of an oral epithelial barrier.

Oral epithelial barrier consists of closely controlled structure of the stratified squamous epithelium, which is the gateway to human bodies and encounters a huge burden of microbial, airborne and dietary antigens, as well as masticatory damage. Once this barrier is destroyed, it will trigger bone loss, tissue damage and microbial dysbiosis and lead to diseases, such as periodontitis, oral mucosal diseases and oral cancer. Recently, increasing evidences showed that different factors including microorganism, saliva, proteins and immune components have been considered to play a critical role in the disruption of oral epithelial barrier. Herein, we discussed mechanisms governing the maintenance of oral epithelial barrier. Besides, the role of oral epithelial barrier failure in oral carcinogenesis will also be talked about.

Porphyromonas gingivalis Promotes 4-Nitroquinoline-1-Oxide-Induced Oral Carcinogenesis With an Alteration of Fatty Acid Metabolism.

Microbiota has been widely considered to play a critical role in human carcinogenesis. Human papilloma virus, hepatitis B and C virus, and Helicobacter pylori are implicated in the pathogenesis of cancer of uterine cervix, liver, and stomach, respectively. However, whether Porphyromonas gingivalis (P. gingivalis), a common Gram negative oral bacteria, is associated with oral carcinogenesis still remains unclear and its underlying mechanism needs to be addressed. Here, we established a combined experimental system of 4NQO-induced oral carcinoma model and chronic periodontitis model and investigated the effects of P. gingivalis infection on oral carcinogenesis and fatty acid metabolism during oral carcinogenesis. The data showed that in this animal model, P. gingivalis infection induced mice periodontitis, increased the tongue lesion size and multiplicity of each mouse and promoted oral cancer development. P. gingivalis treatment significantly increased the level of free fatty acids and altered the fatty acid profile in tongue tissues and the serum of mice. And P. gingivalis induced the formation of fatty liver of the mice. Besides, immunohistochemical analysis and qRT-PCR showed that the expression of fatty-acid synthase and acetyl-CoA carboxylase 1 were increased in the tongue and liver tissues of 4NQO-treated mice infected with P. gingivalis. These results showed that P. gingivalis promoted oral carcinogenesis and aggravated disturbance of fatty acid metabolism, indicating a close association among P. gingivalis, lipid metabolic and oral carcinogenesis.

Adsorption of fibronectin on salt-etched polyelectrolyte multilayers and its roles in mediating the adhesion and migration of vascular smooth muscle cells.

Protein adsorption on biomaterials strongly mediates the subsequent cell responses. Here adsorption of fibronectin (Fn) on salt-treated PEI(PSS/PDDA)7 multilayers was characterized. The amounts of adsorbed Fn increased linearly along with the increase of thickness of multilayers pretreated with 1 M and 5 M NaCl solutions (Multilayer-1M and 5M), but was independent on the thickness of Multilayer-3M. The normalized relative RGD activity of Fn were significantly higher on the Multilayer-3M than on others. By comparison of cellular behaviors of VSMCs being cultured in the normal and Fn-depleted serum-containing medium, the significant role of Fn on modulating the behaviors of VSMCs was verified. The Fn adsorption model and its role on linking the biomaterials surface to the VSMCs behaviors are proposed.

A novel antithrombotic coronary stent: lysine-poly(HEMA)-modified cobalt-chromium stent with fibrinolytic activity.

Prevention of coagulation appears not to be possible when a foreign surface is in contact with blood; the alternative concept of a clot lysing surface has therefore been suggested. In this work, a mimic of the fibrinolytic system was constructed on L605 cobalt-chromium coronary stents. Lysine which, immobilized on a surface, has been shown previously to adsorb plasminogen in contact with blood was attached to the stent using poly(2-hydroxyethyl methacrylate) (poly(HEMA)) as a spacer. The lysine-poly(HEMA) modified stent was shown to have low nonspecific protein adsorption and to bind plasminogen in high quantity from plasma. Following exposure to plasma and treatment with tissue plasminogen activator, the lysine-modified stents showed clot-lysing properties in vitro while the unmodified L605 stents did not. It was shown that the modified stents retained their clot lysing properties after 24 h exposure to plasma.

Synthesis, characterization and biomedical properties of UV-cured polyurethane acrylates containing a phosphorylcholine structure.

In order to develop a simple, economical and rapid approach to incorporate 2-methacryloyloxyethyl phosphorylcholine (MPC) with other monomers without any solvent, we prepared a series of ultraviolet cured poly(urethane acrylate) (PUA) membranes containing different MPC content. Their chemical structure and surface properties were investigated by FT-IR, XPS, water swelling ratio and water contact angle measurement, while the biocompatibilities were evaluated through fibrinogen adsorptions, platelet adhesion and plasma recalcification time determination. The results demonstrate that the phosphorylcholine (PC) groups were successfully introduced into the PUA system by the UV-curing approach and the all PC-containing membranes showed better biocompatibility than those without PC moiety. The UV-curing method is potentially to be applied in the coating of medical devices which require biocompatibility and manufacturing efficiency.

Novel CeO2 yolk-shell structures loaded with tiny Au nanoparticles for superior catalytic reduction of p-nitrophenol.

Direct fabrication of core-shell or yolk-shell functional nanomaterials via a facile template-free method remains a challenge. In this work, we present a novel approach that involves straightforward chemical transformation and thermal treatment of the infinite coordination polymer particles to obtain composition-tunable CeO(2) yolk-shell structures. Uniform CeO(2) yolk-shell hollow spheres with a high surface area are promising support materials for tiny gold nanoparticles (ca. 4 nm), forming Au-CeO(2) nanocomposites which exhibit a remarkable catalytic activity and high stability for the reduction of p-nitrophenol. A possible mechanism for the formation of CeO(2) yolk-shell microspheres is also proposed.

Lysine-poly(2-hydroxyethyl methacrylate) modified polyurethane surface with high lysine density and fibrinolytic activity.

We have developed a potentially fibrinolytic surface in which a bioinert polymer is used as a spacer to immobilize lysine such that the ε-amino group is free to capture plasminogen when in contact with blood. Adsorbed plasminogen can be activated to plasmin and potentially dissolve nascent clots formed on the surface. In previous work lysine was immobilized through a poly(ethylene glycol) (PEG) spacer; however, the graft density of PEG was limited and the resulting adsorbed quantity of plasminogen was insufficient to dissolve clots efficiently. The aim of the present work was to optimize the surface using graft-polymerized poly(2-hydroxyethyl methacrylate) (poly(HEMA)) as a spacer to increase the grafting density of lysine. Such a poly(HEMA)-lysine modified polyurethane (PU) surface is expected to have increased plasminogen binding capacity and clot lysing efficiency compared with PEG-lysine modified PU. A lysine density of 2.81 nmol cm(-2) was measured on the PU-poly(HEMA)-Lys surface vs. 0.76 nmol cm(-2) on a comparable PU-PEG-Lys surface reported previously. The poly(HEMA)-lysine-modified surface was shown to reduce non-specific (fibrinogen) adsorption while binding plasminogen from plasma with high affinity. With increased plasminogen binding capacity these surfaces showed more rapid clot lysis (20 min) in a standard in vitro assay than the corresponding PEG-lysine system (40 min). The data suggest that poly(HEMA) is superior to PEG when used as a spacer in the immobilization of bioactive molecules at high density. This method of modification may also provide a generic approach for preparing bioactive PU surfaces of high activity and low non-specific adsorption of proteins.