Analysis of Retinol Binding Protein 4 and ABCA4 Gene Variation in Non-Neovascular Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) may be associated with ABCA4 variants and is characterized by the accumulation of visual cycle-byproduct lipofuscin. Reducing retinol-binding protein 4 (RBP4), a retinol transporter protein, may reduce lipofuscin production. This study aims to assess the associations between plasma RBP4, the ABCA4 variation, and AMD severity. Sixty-seven participants were grouped into healthy/mild AMD (n = 32) and severe AMD (n = 35) groups. The latter group was older than the former group and had higher levels of RBP4 (36.8 ± 8.3 vs. 30.4 ± 7.0 µg/mL, p = 0.0012). The ten participants with six ABCA4 linked-variants had higher RBP4 than those without (37.8 ± 7.7 vs. 32.4 ± 7.9 µg/mL; p = 0.026), and eight of them had severe AMD. Univariate analyses showed that severe AMD was related to older age (OR, 1.26; 95% CI, 1.13-1.40; p < 0.0001) and to higher RBP4 levels (OR, 1.12; 95% CI, 1.04-1.20; p = 0.003), whereas the linked ABCA4 variants had no associations. After adjustment, however, only age remained significantly associated with severe AMD. This pilot study shows a trend of higher plasma RBP4 levels in severe AMD or the ABCA4-linked variants, and further age-matched studies are warranted.

Biomechanical effects of different numbers and locations of screw-in clavicle hook plates.

Purpose: We sought to analyze the biomechanical effects which both different numbers and locations of screws have on three different clavicle hook plates, as well as any possible causes of sub-acromial bone erosion and peri-implant clavicular fractures. Methods: This study built thirteen groups of finite element models using three different clavicle hook plates (short plates, long plates, and posterior hook offset plates) in varying numbers and locations of the screws. The von Mises stress distribution of the clavicle and hook plate, as well as the reaction force of the acromion was evaluated. Results: The results show that inserting screws in all available screw holes on the hook plate produces a relatively large reaction force on the acromion, particularly in the axial direction of the bone plate. The fewer the screws implanted into the clavicle hook plate, the larger the area of high-stress distribution there is in the middle of the clavicle, and also, the higher the stress distribution on the clavicle hook plate. Conclusion: This study provides orthopedic physicians with the biomechanical analysis of different numbers and locations of screws in clavicle hook plates to help minimize surgical complications.

An Update to Hallmarks of Cancer.

In the last decade, there has been remarkable progress in research toward understanding and refining the hallmarks of cancer. In this review, we propose a new hallmark - "pro-survival autophagy." The importance of pro-survival autophagy is well established in tumorigenesis, as it is related to multiple steps in cancer progression and vital for some cancers. Autophagy is a potential anti-cancer therapeutic target. For this reason, autophagy is a good candidate as a new hallmark of cancer. We describe two enabling characteristics that play a major role in enabling cells to acquire the hallmarks of cancer - "tumor-promoting microenvironment and macroenvironment" and "cancer epigenetics, genome instability and mutation." We also discuss the recent updates, therapeutic and prognostic implications of the eight hallmarks of cancer described by Hanahan et al. in 2011. Understanding these hallmarks and enabling characteristics is key not only to developing new ways to treat cancer efficiently but also to exploring options to overcome cancer resistance to treatment.

Analysis of Micro-Machining Process for External Thread of Micro Round Tube.

This study aims to analyze the stainless steel micro round tube external threading process for the influence of different outer threading pitches (0.25 mm, 0.4 mm) and outer diameters (Ø1.9, Ø1.94, Ø2). This study also analyzes the effects of different friction factors (0.1, 0.3, 0.5, 0.7, and 0.9) and different tube thicknesses (0.4, 0.45, 0.5, 0.55, and 0.6 mm) on the threading process. This study considers size effect to use corrected material parameters for the microtube to conduct the finite element analysis by DEFORM-3D software. The goal is to understand stainless steel (SUS304) micro round tube threading and the difference by using macro material parameter analysis. The historic forming data from the simulation and experiment of threading processing are presented, and the corresponding stress/strain distribution and thread shape are also calculated. The experiment results are compared to the simulation results to verify the reliability of this analysis method. The result shows that the torque/stress/strain obtained by the modified model is always lower than by Swift's model. It means that the size effect can be considered to apply on the forming process and provided proper torque to form the external thread of the micro round tube, e.g., the maximum torque of the round die for M2 × 0.25 occurs over the fourth stroke. For the influence of the outer diameter of the micro round tube, the larger diameter induces the larger maximum torque on the round die for M2 × 0.4, but for the smaller pitch of M2 × 0.25, the larger maximum torque is not influenced by the diameter of the tube. When the pitch of the round die is increased, the torque, stress and strain are also increased relatively. As the friction factor and torque between the round die and tube increase, the stress and strain become lower. Changing the tube thickness will not significantly change the torque, the stress, and the strain. These results guide the simulation and experiment of optimized micro round tube threading development and design to reduce cost and increase product quality.

Biomechanical analysis of the treatment of intertrochanteric hip fracture with different lengths of dynamic hip screw side plates.

BACKGROUND: Dynamic hip screw (DHS) is a common implant used to treat stable-type intertrochanteric hip fractures. There are many factors that can affect the success rate of the surgery, including the length of side plates. It is therefore important to investigate the biomechanical effect of different DHS side plates on bones. OBJECTIVE: In order to reduce the likelihood of an implant failure, the aim of this study was to use finite element analysis (FEA) to investigate and understand the effect of side plates with different lengths in DHS. METHODS: In this FEA study, a 3D model with cortical bone, cancellous bone, side plate, lag screw, and cortical screws to simulate the implantation of DHS with different lengths of side plate (2-hole, 4-hole, and 6-hole) for intertrochanteric hip fractures was constructed. The loading condition was used to simulate the force (400 N) on the femoral head and the stress distribution on the lag screw, side plate, cortical screws, and femur was measured. RESULTS: The highest stress points occured around the region of contact between the screw and the cortical bones. The stress on the femur at the most distal cortical screw was the greatest. The shorter the length of the side plate, the greater the stress on the cortical screws, resulting in an increased stress on the femur surrounding the cortical screws. CONCLUSIONS: The use of DHS with 2-hole side plate may increase the risk of side plate pull-out. The results of this study provide a biomechanical analysis for selection of DHS implant lengths that can be useful for orthopaedic surgeons.

Glycans on influenza hemagglutinin affect receptor binding and immune response.

Recent cases of avian influenza H5N1 and the swine-origin 2009 H1N1 have caused a great concern that a global disaster like the 1918 influenza pandemic may occur again. Viral transmission begins with a critical interaction between hemagglutinin (HA) glycoprotein, which is on the viral coat of influenza, and sialic acid (SA) containing glycans, which are on the host cell surface. To elucidate the role of HA glycosylation in this important interaction, various defined HA glycoforms were prepared, and their binding affinity and specificity were studied by using a synthetic SA microarray. Truncation of the N-glycan structures on HA increased SA binding affinities while decreasing specificity toward disparate SA ligands. The contribution of each monosaccharide and sulfate group within SA ligand structures to HA binding energy was quantitatively dissected. It was found that the sulfate group adds nearly 100-fold (2.04 kcal/mol) in binding energy to fully glycosylated HA, and so does the biantennary glycan to the monoglycosylated HA glycoform. Antibodies raised against HA protein bearing only a single N-linked GlcNAc at each glycosylation site showed better binding affinity and neutralization activity against influenza subtypes than the fully glycosylated HAs elicited. Thus, removal of structurally nonessential glycans on viral surface glycoproteins may be a very effective and general approach for vaccine design against influenza and other human viruses.

Iron oxide/gold core/shell nanoparticles for ultrasensitive detection of carbohydrate-protein interactions.

Changes in the expression of cell surface glycan are often associated with malignant metastasis. The expression level may be dramatically enhanced during tumor progression. A highly sensitive assay that is capable of detecting low levels of cancer-associated carbohydrate antigens can be a powerful tool for early diagnosis. In this work, an ultrasensitive glycans array using iron oxide/gold core/shell nanoparticles conjugated with antibodies or proteins is developed. A magnetic field is applied to quickly bring nanoparticle labeled proteins or antibodies from a solution to an array of carbohydrates immobilized on glass slides and to help them to encounter the carbohydrates at very low concentration. The gold shell provides a well established platform for conjugation of biomolecules. Well-defined recognition systems, namely, mannose derivatives (Man1, Man4, and Man9) with a mannose binding lectin (Concanavalin A) and a stage-specific embryonic antigens-3 (SSEA-3) with a monoclonal antibody (anti-SSEA-3) were chosen to establish this detection tool. Array systems were conducted to determine their surface dissociation constant (K(D,surface)) and their binding specificity for qualitative and quantitative analysis of carbohydrate-protein and carbohydrate-antibody interactions. When coupled with a signal amplification method based on nanoparticle-promoted reduction of silver, the sensitivity of an iron oxide/gold core/shell nanoparticle-based assay reached to subattomole level in carbohydrate detection.

HA-pseudotyped retroviral vectors for influenza antagonist screening.

Influenza infections are initiated by the binding of the influenza hemagglutinin (HA) and the cellular receptor sialic acids. The binding is followed by internalization, endocytosis, and uncoating to release the influenza genome to the cytoplasm. It is conceivable that specific inhibitors that antagonize any one of these events could prevent the replication of influenza infections. The authors made HA pseudotyped retroviral vectors that express luciferase reporter activities upon transduction to several recipient cells. The transduction of the HA-pseudotype virus particles (HApp) was mediated through the specific interactions between an avian HA and the terminal disaccharides of sialic acid (SA) and galactose (Gal) in alpha-2,3 linkage. The HApp-mediated transduction method was used to develop a high-throughput screening assay and to screen for hits from a fermentation extract library. Specific hits that inhibited the HA-mediated but were noninhibitory to the vesicular stomatitis virus-mediated pseudoviral transductions were identified. A few of these hits have anti-influenza activities that prevent the replication of both H1N1 (WSN) and H5N1 (RG14) influenza viruses.

Glycan microarray of Globo H and related structures for quantitative analysis of breast cancer.

Cancer-associated carbohydrate antigens are often found on the surface of cancer cells. Understanding their roles in cancer progression will lead to the development of new therapeutics and high-sensitivity diagnostics for cancers. Globo H is a member of this family, which is highly expressed on breast cancer cells. Here, we report the development of a glycan microarray of Globo H and its analogs for measurement of the dissociation constants on surface (K(D,surf)) with three different monoclonal antibodies (VK-9, Mbr1, and anti-SSEA-3), to deduce their binding specificity. The glycan microarray was also used to detect the amount of antibodies present in the plasma of breast cancer patients and normal blood donors. It was shown that the amount of antibodies against Globo H from breast cancer patients were significantly higher than normal blood donors, providing a new tool for possible breast cancer diagnosis. Compared with the traditional ELISA method, this array method required only atto-mole amounts of materials and is more effective and more sensitive (5 orders of magnitude). The glycan microarray thus provides a new platform for use to monitor the immune response to carbohydrate epitopes after vaccine therapy or during the course of cancer progression.

Glycan arrays on aluminum-coated glass slides.

We have developed a novel method of immobilizing glycans onto aluminum-coated glass (ACG) slides for potential use in disease diagnosis and drug discovery. The quality of these sugar chips can be assessed by mass spectrometry and fluorescence measurements with high sensitivity. The unique properties of ACG slides include: 1) the metal oxide layer on the surface can be activated for grafting organic compounds such as modified oligosaccharides; 2) the surface remains electrically conductive, and the grafted oligosaccharides can be simultaneously characterized by mass spectrometry and carbohydrate-binding assay; and 3) the slides are more sensitive than transparent glass slides in binding analysis. To demonstrate this, we synthesized a model compound of mannose with a built-in photocleavable linker bound to the ACG slide surface. The molecular weight of the grafted mannose was identified by mass spectrometry, and the slide was subjected to biotinylated ConA binding followed by Cy3-tagged streptavidin detection. This method was further extended to the preparation of glycan arrays containing lactose and the cancer antigen Globo H.