[Imaging study on determining the rationality of atlantoaxial fixation angle based on the ratio of line segments between anatomical markers on lateral X-ray films].

Objective: To propose a method to determine the unreasonableness of the fixed angle in posterior atlantoaxial fusion surgery based on the ratio of line segments between anatomical landmarks of the atlantoaxial joint. Methods: A cross-sectional study was conducted. According to the inclusion criteria, a screening was performed on the database of asymptomatic volunteers who had full-spine lateral X-ray films taken at the Second Affiliated Hospital of Wenzhou Medical University from May 2016 to May 2021. A total of 207 volunteers were included, comprising 98 males with an age of (40.68±13.87) years and 109 females with an age of (42.64±14.45) years. On the lateral X-ray film, a line (L) parallel to the posterior margin of the odontoid process was drawn at the posterior edge of the lower articular surface of the axis (a), intersecting the atlas at points b, c, and d. The line segments ab, bd, bc, and the C1-C2 angle were measured, and the ratios of bd/ab and bc/ab were calculated. The ability of bd/ab and bc/ab to predict the unreasonable fixed angle of the atlantoaxial joint (≥22°) was analyzed by receiver operating characteristic (ROC) curve analysis in both male and female. The areas under the ROC curves (AUC) were calculated, and the performance of the two prediction methods was compared using the Delong's test. The cutoff value for distinguishing the unreasonableness of the C1-C2 angle and the sensitivity and specificity were calculated. Results: The ROC curve analysis in the male group showed that the AUC of bc/ab for predicting the unreasonable C1-C2 angle was 0.791 (95%CI: 0.696-0.867, P<0.001), with a cutoff value of 0.449, sensitivity of 97.3%, and specificity of 70.0%. The performance was significantly better than that of bd/ab (cutoff value 1.100, AUC=0.532, 95%CI: 0.428-0.634, sensitivity 26.3%, specificity 83.3%, P<0.001). The ROC curve analysis in the female group showed that the AUC of bc/ab for predicting the unreasonable C1-C2 angle was 0.804 (95%CI: 0.745-0.852, P<0.001), with a cutoff value of 0.488, sensitivity of 90.5%, and specificity of 58.6%. The performance was significantly better than that of bd/ab (cutoff value 0.960, AUC=0.687, 95%CI: 0.624-0.748, sensitivity 90.5%, specificity 44.8%, P=0.041). Conclusions: The bc/ab value can be used as an effective indicator to predict the unreasonable C1-C2 angle in posterior atlantoaxial fusion surgery with high diagnostic accuracy. The cutoff value for males is<0.449, and for females is<0.488.

A binary pulsar in a 53-minute orbit.

Spider pulsars are neutron stars that have a companion star in a close orbit. The companion star sheds material to the neutron star, spinning it up to millisecond rotation periods, while the orbit shortens to hours. The companion is eventually ablated and destroyed by the pulsar wind and radiation1,2. Spider pulsars are key for studying the evolutionary link between accreting X-ray pulsars and isolated millisecond pulsars, pulsar irradiation effects and the birth of massive neutron stars3-6. Black widow pulsars in extremely compact orbits (as short as 62 minutes7) have companions with masses much smaller than 0.1 M⊙. They may have evolved from redback pulsars with companion masses of about 0.1-0.4 M⊙ and orbital periods of less than 1 day8. If this is true, then there should be a population of millisecond pulsars with moderate-mass companions and very short orbital periods9, but, hitherto, no such system was known. Here we report radio observations of the binary millisecond pulsar PSR J1953+1844 (M71E) that show it to have an orbital period of 53.3 minutes and a companion with a mass of around 0.07 M⊙. It is a faint X-ray source and located 2.5 arcminutes from the centre of the globular cluster M71.

Electropolishing influence on biocompatibility of additively manufactured Ti-Nb-Ta-Zr: in vivo and in vitro.

Balling defect of the additively manufactured titanium lattice implants easily leads to muscle tissue rejection, which might cause failure of implantation. Electropolishing is widely used in surface polishing of complex components and has potential to deal with the balling defect. However, a clad layer could be formed on the surface of titanium alloy after electropolishing, which may affect the biocompatibility of the metal implants. To manufacture lattice structured ß-type Ti-Ni-Ta-Zr (TNTZ) for bio-medical applications, it is necessary to investigate the impact of electropolishing on material biocompatibility. In this study, animal experiments were conducted to investigate the in vivo biocompatibility of the as-printed TNTZ alloy with or without electropolishing; and proteomics technology was used to elaborate the results. The following conclusions were drawn: (a) a 30% oxalic acid electropolishing treatment was effective in solving balling defects, and ~21 nm amorphous clad layer would be formed on the surface of the material after polishing; (b) the electropolished TNTZ suggested decreased cell cytotoxicity and improved blood biocompatibility as compared to as-printed TNTZ; (c) the amorphous clad layer could make a barrier to prevent Ta and Zr ions from penetrating into the muscle tissue, and could form a good tissue regeneration at the implantation site during 4 weeks, indicating that the electropolished TNTZ has the potential as implants; and (d) the cells attached to the electropolished TNTZ showed higher antioxidant capacity but less proliferation than attached to as-printed TNTZ.

[Imaging study on the safety of axial pedicle screw placement by the position of the screw trajectory tip on the anteroposterior and lateral radiographs].

Objective: To propose a method to judge the safety of axial pedicle screw placement based on the position of the tip of the screw trajectory on the anteroposterior and lateral X-ray radiographs. Methods: The cervical CT data of 40 patients admitted to the Second Affiliated Hospital of Wenzhou Medical University from December 2020 to December 2021 were selected, including 24 males and 16 females, with a mean age of (47.6±13.2) years. Based on the three-dimensional model reconstruction of Mimics software and its function of X-ray, the transmission of the axial pedicle screw and its anteroposterior and lateral films was simulated. The position of the tip of the simulated screw trajectory was divided into 5 regions (regions Ⅰ-Ⅴ) from the inside to the outside on the anteroposterior virtual radiographs, and the upper and lower regions (regions a, b) on the lateral virtual radiographs. By adjusting the direction of the screw, the tip of the screw was located in the corresponding 10 regions (80 screws in each area) on the virtual projections of the anteroposterior and lateral virtual radiographs respectively, and its accuracy was analyzed by CT to determine whether each screw penetrated the medial wall of the pedicle or vertebral artery foramen. The anteroposterior and lateral X-rays and postoperative CT data of 34 patients who underwent axial pedicle screw placement (67 axial pedicle screws were placed in total) from January 2014 to December 2021 were collected, including 18 males and 16 females, with a mean age of (45.8±14.1) years. The position of the tip of the screw trajectory on the anteroposterior and lateral films was divided in the same way. The number of screws in the corresponding 10 positions was counted, and CT analysis was used to determine whether each screw penetrated the medial wall of the axial pedicle or the vertebral artery foreman. Results: The results of the imaging simulation screw placement study showed that the perforation rate of the vertebral artery foramen in region Ⅳ and Ⅴ was 75.0% (120/160) and 100% (160/160), respectively, while the perforation rate of the medial wall of the axial pedicle in the region Ⅰ was 85.6%(137/160). The failure rate in regions Ⅱ and Ⅲ was relatively lower, and the performance of simulated screws located in the region a was better than those in region b. The perforation rates of the medial wall in regions (a-Ⅱ) and (a-Ⅲ) was 7.5% (6/80) and 0 (0/80), respectively, and the perforation rates of the vertebral foramen was 0 (0/80) and 21.3% (17/80), respectively. The retrospective imaging study also showed a higher rate of placement failure in regions Ⅰ, Ⅳ and Ⅴ, and relatively lower in regions Ⅱ and Ⅲ. There were total of 15 screws in region a-Ⅱ and a-Ⅲ, and no destruction of the medial wall of the axial pedicle and the vertebral artery foreman occurred there. Conclusions: Regions a-Ⅱ and a-Ⅲ are the "safety areas" of the tip of the pedicle screw trajectory in the axial vertebra. By analyzing the tip of the pedicle screw trajectory on the anteroposterior and lateral radiographs, the operator can determine the reasonable trajectory of axial pedicle screw placement, prevent the injury of the cervical spinal cord and vertebral artery, and reduce the risk of operation.

[Clinical characteristics and prognostic factors of 1 166 patients with uveal melanoma].

Objective: To analyze the clinical characteristics and survival of Chinese uveal melanoma (UM) patients. Methods: It was a retrospective case series study. Clinical data and demography characteristics of 1 166 UM patients who were diagnosed in Beijing Tongren Hospital from January 2004 to January 2020 were collected. The disease was followed up after informed consent was obtained. Kaplan-Meier plots were used to visualize survival outcomes, and the different risk groups were compared using the Log-rank test. The multivariate Cox proportional hazards model was used to select independent prognostic risk factors. Results: A total of 1 166 individuals (598 men, 568 women) were included in this study. The average age was (47.6±12.2) years. Median follow-up time was 38 months. Treatment included episcleral brachytherapy in 881 (75.6%) patients, local tumor resection in 38 (3.2%) patients, laser therapy in 115 (9.9%) patients and primary enucleation in 119 (10.2%) patients. In 120 patients out of the 881 patients with primary brachytherapy, enucleation was performed due to an increasing tumor size or uncontrolled neovascular glaucoma. The Kaplan-Meier survival analysis showed the 5-and 10-year metastasis rates were 18.5% and 26.8%, and the melanoma-related mortality rates were 13.6% and 22.2%, respectively. The Log-rank test showed that patient age (χ²=5.01) and gender (χ²=7.19), as well as tumor grade (χ²=49.11), shape (χ²=34.73), location (χ²=18.60), pathological type (χ²=8.07), presence of subretinal fluid (χ²=15.71) and ciliary body involvement (χ²=19.72) were factors influencing patient prognoses (all P<0.05). In the multivariate Cox analysis, the T2, T3, T4 tumors (compared with the T1 tumor, HR=4.41, 6.82, 10.49), subretinal fluid (HR=1.98), ciliary body involvement (HR=1.79), being male (HR=1.53) and advanced age (greater than 53 years old) (HR=1.83) were independent risk factors for poor prognoses (all P<0.05). Conclusions: UM occurs at a significantly earlier age and non-pigmented tumors represent smaller proportion in Chinese patients. Higher T-stage, presence of subretinal fluid, ciliary body involvement, advanced age, and being male are independent risk factors for poor outcomes.

[Exploring the effects of artesunate and fuzheng huayu decoction on mitochondria in the treatment of schistosomiasis liver fibrosis].

Objective: To compare the effects of artesunate (Art) and fuzheng huayu decoction on mitochondrial autophagy in the treatment of schistosomiasis liver fibrosis. Methods: Eighty C57BL/6 female mice were randomly divided into healthy control group, infection group, Art treatment group and Fuzheng Huayu Decoction treatment group, with 20 mice in each group. Mice in the infection group and treatment group were infected with 16 Schistosoma japonicum cercariae. After 6 weeks, praziquantel (300 mg/kg) was used for 2 days to kill the worms. The Art treatment group was treated with intraperitoneal injection of 100 mg/kg/day, while the Fuzheng Huayu Decoction treatment group was fed 16g of fuzheng huayu decoction per 1kg per day. After 6 weeks, fresh liver tissues of the four groups were collected. Masson staining and Western blot were used to observe the succinate dehydrogenase subunit A (SDHA) and malate dehydrogenase (MDH2), citrate synthase (CS), ketoglutarate dehydrogenase (OGDH), and target of rapamycin 1 (mTORC1) pathway involved in mitochondrial tricarboxylic acid cycle in liver tissues. The relative expression levels of adenylate activated protein kinase (AMPK) and mitochondrial autophagy pathway kinase (PINK1) were detected. Liver tissue samples were extracted from each group to detect the mitochondrial oxygen consumption rate. Two-way ANOVA was used to compare the significance and difference between two sets of samples. Results: Masson staining showed that the infection group mice had significantly higher liver fibrosis area than the healthy control group, while the Art treatment group and Fuzheng Huayu Decoction treatment group mice had lower liver fibrosis area than the infection group. Western blot analysis showed that the infection group (0.82 ± 0.05) had significantly lower relative expression of SDHA protein than the healthy control group (1.00 ± 0.05) (t = 11.23, P = 0.0035), while the Art treatment group (0.73 ± 0.05) had significantly higher relative expression of SDHA protein than the infection group (t = 10.79, P = 0.0073). However, there was no significant change in Fuzheng Huayu Decoction treatment group (0.98±0.05) (t = 1.925, P = 0.1266). The relative expression of p-AMPK protein was significantly higher in the infection group (1.15 ±0.05) than in the healthy control group (0.98 ± 0.07, t = 12.18, P = 0.0029), and the expression of p-AMPK in the Art treatment group (0.50 ± 0.05) was significantly lower than the infection group (t = 11.78, P = 0.0032). The relative protein expression of AMPK was significantly lower in the infection group (0.80 ± 0.05) than in the healthy control group (1.00 ± 0.05, t = 10.53, P = 0.0046). The expression of AMPK was significantly lower in the Art treatment group (0.54 ± 0.05) than in the infection group (T = 13.98, P = 0.0036). The relative expression of p-mTORC1 protein (0.93 ± 0.08) was not significantly different in the infection group than in the healthy control group (t = 2.28, P = 0.065), while the Art treatment group (0.63 ± 0.05) had significantly lower relative expression of p-mTORC1 protein than the infection group (t = 10.58, P = 0.029). The expression of p-mTORC1/ m-TORC1 was not significantly different in the infection group (0.98 ± 0.03) than in the healthy control group (0.97 ± 0.03, t = 0.98, P = 0.085), while the Art treatment group (0.63 ± 0.05) had significantly lower relative expression of p-mTORC1/ m-TORC1 than the infection group (t = 14.58, P = 0. 009). The relative protein expression of PINK1 was significantly lower in the infection group (0.55 ± 0.05) than in the healthy control group (1.00 ± 0.03, t = 13.49, P = 0.0011), while the Art treatment group (1.21 ± 0.05, t = 9.98, P = 0.0046) and Fuzheng Huayu Decoction treatment group (1.31 ±0.35, t = 6.98, P = 0.027) had significantly higher relative protein expression of PINK1 than the infection group. Mitochondrial function tests showed that after adding substrate complex II, the oxygen consumption of the infection group was lower than the healthy control group, while the Art treatment group and the Fuzheng Huayu Decoction treatment group had higher oxygen consumption than the infection group. The oxygen consumption was significantly lower after adding the substrate complex III in the infection group than the healthy control group, while the Art treatment group and Fuzheng Huayu Decoction treatment group had higher oxygen consumption than the infection group. Conclusion: Art can alleviate schistosomiasis liver fibrosis by inhibiting AMPK/mTORC1 signaling pathway activity and enhancing mitochondrial oxygen consumption, autophagy and SDHA expression.

Diverse polarization angle swings from a repeating fast radio burst source.

Fast radio bursts (FRBs) are millisecond-duration radio transients1,2 of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star magnetospheres3-5 or relativistic shocks far from the central energy source6-8. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters9,10 or variable polarization angles in some other apparently one-off events11,12. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.

Three phytotoxins produced by Neopestalotiopsis clavispora, the causal agent of ring spot on Kadsura coccinea.

Phytotoxins are widely found in plant pathogens. In recent years, many diseases caused by Neopestalotiopsis clavispora have been reported. To better understand the pathogenicity of N. clavispora, a solid fermentation strategy was employed to isolate and identify virulence factors afritoxinone B, afritoxinone A and oxysporone. The phytotoxic activities of these toxins were evaluated. Oxysporone exhibited high levels of phytotoxic activity after 72 h and the lesion area ranged from 21.5-84.3 mm2 after 9 days of treatment. The phytotoxic activities of the other two compounds were lower than that for oxysporone. The phytotoxic activity towards non-host organisms was also assessed for the three analyzed compounds; phytotoxic activity was observed in each case. Based on these results, we conclude that oxysporone is the main virulence factor in N. clavispora. We also suggest that each of the three compounds were non-host-specific toxins (NHST). To our knowledge, this is the first study to analyze phytotoxins produced by N. clavispora.

Bimorph material/structure designs for high sensitivity flexible surface acoustic wave temperature sensors.

A fundamental challenge for surface acoustic wave (SAW) temperature sensors is the detection of small temperature changes on non-planar, often curved, surfaces. In this work, we present a new design methodology for SAW devices based on flexible substrate and bimorph material/structures, which can maximize the temperature coefficient of frequency (TCF). We performed finite element analysis simulations and obtained theoretical TCF values for SAW sensors made of ZnO thin films (~5 µm thick) coated aluminum (Al) foil and Al plate substrates with thicknesses varied from 1 to 1600 µm. Based on the simulation results, SAW devices with selected Al foil or plate thicknesses were fabricated. The experimentally measured TCF values were in excellent agreements with the simulation results. A normalized wavelength parameter (e.g., the ratio between wavelength and sample thickness, λ/h) was applied to successfully describe changes in the TCF values, and the TCF readings of the ZnO/Al SAW devices showed dramatic increases when the normalized wavelength λ/h was larger than 1. Using this design approach, we obtained the highest reported TCF value of -760 ppm/K for a SAW device made of ZnO thin film coated on Al foils (50 µm thick), thereby enabling low cost temperature sensor applications to be realized on flexible substrates.

First Report of Corynespora Leaf Spot of Eucalyptus in China.

Eucalyptus is widely planted in the tropics and subtropics, and it has become an important cash crop in Southern China because of its fast-growing nature. In the Guangxi Province of southern China, Eucalyptus is produced on approximately 2 million ha, and two dominant asexual clones, Guanglin No. 9 (E. grandis × E. urophylla) and DH3229 (E. urophylla × E. grandis), are grown. Diseases are an increasing threat to Eucalyptus production in Guangxi since vast areas are monocultured with this plant. In June 2013, a leaf spot disease was observed in eight out of 14 regions in the province on a total of approximately 0.08 million ha of Eucalyptus. Initially, the lesions appeared as water-soaked dots on leaves, which then became circular or irregular shaped with central gray-brown necrotic lesions and dark red-brown margins. The size of leaf spots ranged between 1 and 3 mm in diameter. The main vein or small veins adjacent to the spots were dark. The lesions expanded rapidly during rainy days, producing reproductive structures. In severe cases, the spots coalesced and formed large irregular necrotic areas followed by defoliation. The causal fungus was isolated from diseased leaves. Briefly, the affected leaves were washed with running tap water, sterilized with 75% ethanol (30 s) and 0.1% mercuric dichloride (3 min), and then rinsed three times with sterilized water. Small segments (0.5 to 0.6 cm2) were cut from the leading edge of the lesions and plated on PDA. The plates were incubated at 25°C for 7 to 10 days. When mycelial growth and spores were observed, a single-spore culture was placed on PDA and grown in the dark at 25°C for 10 days. A pathogenicity test was done by spraying a conidial suspension (5 × 105 conidia ml-1) of isolated fungus onto 30 3-month-old leaves of Guanglin No. 9 seedlings. The plants were covered with plain plastic sheets for 7 days to keep the humidity high. Lesions similar to those observed in the forests were observed on the inoculated leaves 7 to 10 days after incubation. The same fungus was re-isolated. Leaves of control plants (sprayed with sterilized water) were disease free. Conidiophores of the fungus were straight to slightly curved, erect, unbranched, septate, and pale to light brown. Conidia were formed in chains or singly with 4 to 15 pseudosepta, which were oblong oval to cylindrical, subhyaline to pale olivaceous brown, straight to curved, 14.5 to 92.3 µm long, and 3.5 to 7.1 µm wide. The fungus was morphologically identified as Corynespora cassiicola (1). DNA of the isolate was extracted, and the internal transcribed spacer (ITS) region (which included ITS 1, 5.8S rDNA gene of rDNA, and ITS 2) was amplified with primers ITS5 and ITS4. 529 base pair (bp) of PCR product was obtained and sequenced. The sequence was compared by BLAST search to the GenBank database and showed 99% similarity to C. cassiicola (Accession No. JX087447). Our sequence was deposited into GenBank (KF669890). The biological characters of the fungus were tested. Its minimum and maximum growth temperatures on PDA were 7 and 37°C with an optimum range of 25 to 30°C. At 25°C in 100% humidity, 90% of conidia germinated after 20 h. The optimum pH for germination was 5 to 8, and the lethal temperature of conidia was 55°C. C. cassiicola has been reported causing leaf blight on Eucalyptus in India and Brazil (2,3) and causing leaf spot on Akebia trifoliate in Guangxi (4). This is the first report of this disease on Eucalyptus in China. References: (1) M. B. Ellis and P. Holliday. CMI Descriptions of Pathogenic Fungi and Bacteria, No. 303. Commonwealth Mycological Institute, Kew, Surrey, UK, 1971. (2) B. P. Reis, et al. New Dis. Rep. 29:7, 2014. (3) K. I. Wilson and L. R. Devi. Ind. Phytopathol. 19:393, 1966. (4) Y. F. Ye et al. Plant Dis. 97:1659, 2013.

Cholic acid micelles--controlling the size of the aqueous cavity by PEGylation.

Data show that cholic acid (CA) micelles are less densely packed and much smaller than micelles formed by typical surfactants, suggesting that CA derivatives can be used to synthesize drug nanocarriers. Presumably, the formation of internal cavities is favored by the facial characteristics of the CA molecule, i.e. the convex molecular structure that is hydrophobic on one side and hydrophilic on the other. Here, we present a thermodynamical approach to quantify the effect of facial characteristics on forces governing the self-assembling process of CA molecules. We show that facial characteristics favor the entrapment of water molecules at interfaces upon CA aggregation, which weakens the attraction between CA hydrophobic moieties. Our computer simulations suggest that these effects contribute significantly to the tendency of CA molecules to form small "hollow-core" micelles. The attachment of polyethylene glycol (PEG) molecular chains to CA increases the repulsive forces in the system, reducing even further the micelle size. We use the present molecular model and experimental critical micelle concentration (cmc) data for CA-PEG systems to predict the change of the micelle size and cavity volume with the increase of the PEG chain length (x). Our computations indicate that the CA-PEG micelles are good candidates for drug delivery. The structural stability of CA-PEG micelles was further assessed by molecular dynamics simulations. We also tested the drug loading efficiency of this system and found an average of 0.5 mg paclitaxel load per 20 mg of CA-PEG polymer. The present study helps to identify critical parameters that control structural properties of the CA based nanocarriers and suggests practical means to optimize the ratio between micelle size and volume of the internal cavity.

Analysis of rpsL and rrs mutations in Beijing and non-Beijing streptomycin-resistant Mycobacterium tuberculosis isolates from Singapore.

The Beijing genotype of Mycobacterium tuberculosis has frequently been found to be associated with drug resistance. Mutation analysis of the genes encoding 16S rRNA (rrs) and ribosomal protein S12 (rpsL) revealed a high frequency (97/102; 95.1%) of alterations in streptomycin-resistant M. tuberculosis isolates from Singapore, with rpsL K43R being the most common rpsL mutation (82/92; 89%), which was significantly associated with Beijing strains compared to non-Beijing strains (odds ratio = 10.88, 95% confidence interval = 3.48-34.1). This is the first study to report the association of Beijing strains with the rpsL K43R mutation in STR-resistant M. tuberculosis isolates with de novo resistance, as determined by clustering analysis.

Macromolecular scaffolds for immobilizing small molecule microarrays in label-free detection of protein-ligand interactions on solid support.

We explored two macromolecular scaffolds, bovine serum albumin (BSA) and polyvinyl alcohol (PVA), as chemically complementary platforms for immobilizing small molecule compounds on functionalized glass slides. We conjugated biotin molecules to BSA and amine-derivatized PVA and subsequently immobilized the conjugates on epoxy-functionalized glass slides through reaction of free amine residues on BSA and PVA with surface-bound epoxy groups. We studied binding reactions of such immobilized small molecule targets with solution-phase protein probes using an oblique-incidence reflectivity difference scanning optical microscope. The results showed that both BSA and amine-derivatized PVA were effective and efficient as carriers of small molecules with NHS residues and fluoric residues and for immobilization on epoxy-coated solid surfaces. A significant fraction of the conjugated small molecules retain their innate chemical activity.

Effect of fluorescently labeling protein probes on kinetics of protein-ligand reactions.

We studied the effect of fluorescently labeling proteins on protein-ligand reactions. Unlabeled ligands (streptavidin-binding peptides and rabbit immunoglobulin G (IgG) as antigen targets) are immobilized on epoxy-functionalized glass slides. Unlabeled and Cy3-labeled protein probes from the same batch (streptavidin and goat antibodies) subsequently react with the surface-immobilized targets. By monitoring in situ the surface mass density change using an oblique-incidence reflectivity difference scanning microscope (a label-free detector), we measured k(on) and k(off) for streptavidin-peptide reactions and antibody-antigen reaction. We found that (1) equilibrium dissociation constants, defined as K(D) = k(off)/k(on), for streptavidin-peptide reactions increases by a factor of 3-4 when the solution-phase streptavidin is labeled with Cy3 dye and (2) K(D) for reactions of solution-phase goat anti-rabbit antibodies with rabbit IgG targets also change significantly when the goat antibodies are labeled with Cy3 dye.

A novel high-throughput scanning microscope for label-free detection of protein and small-molecule chemical microarrays.

We describe a novel scanning optical microscope based on a polarization-modulated nulling ellipsometry. The new microscope employs a combination of scanning mirror and sample translation and thus enables high-throughput label-free detection of biomolecular microarrays with more than 10 000 protein or small-molecule targets. For illustration, we show the image of a 2760-spot protein microarray on a functionalized glass slide obtained with such a microscope. The new scanning microscope is also capable of determining, in parallel, the real-time binding kinetics of multiple molecular species under aqueous conditions.

Large uniform-sized polymer beads for use as solid-phase supports prepared by ascension polymerization.

Large uniform-sized polymer beads are desirable for "one-bead-one-compound" applications in the combinatorial synthesis of compound libraries. We have developed a technique for the preparation of large polymer spheres with narrow size distributions. Uniform-sized poly(styrene-co-divinylbenzene) beads with diameters in excess of 1 mm have been prepared by free radical polymerization in an ascension process through a heated column. The size of the beads can be adjusted by the diameter of the injection needle and the injection speed. The resin beads can be made porous by the incorporation of a porogen during the preparation; they reach a specific surface area in excess of 200 m(2)/g. The mechanical properties of the spheres and their use in organic synthesis have been studied.