First Report of Elm Yellows Subgroup 16SrV-B Phytoplasma as the Cause of Rose Balsam Phyllody in China

Rose balsam (Impatiens balsamina L.) is an ornamental species frequently cultivated in China and the red flower is often used as nail polish in rural regions. The phytoplasmas previously reported with rose balsam phyllody in China have been classified as aster yellows group (16SrI) (1). In August 2012, some rose balsams were observed with typical phytoplasma symptoms in Handan City, Hebei Province, China, with an incidence of about 70% in the fields. The flowers turned green and petals fascicled. The new leaves wrinkled and deformed and internodes shortened. Infected plants were stunted, matured prematurely, and failed to produce seeds. To confirm phytoplasma infection, 100 mg of plant tissue (leaves, petals) was collected from five symptomatic and four asymptomatic plants and total DNA was extracted using a modified cetyltrimethylammonium bromide (CTAB) method (2). The 16S rDNA gene was amplified by nested PCR using primer pair P1/P7 followed by R16F2n/R16R2 (3). No amplicons were generated with DNA from asymptomatic samples, but amplicons of approximately 1.2 kb were obtained with DNA from five symptomatic samples. The amplified products were purified with aTIANgel midi purification kit (Tiangen, Beijing) and sequenced at the Sangon Biotech facility (Shanghai, China). The sequences of the amplicons were 100% identical and deposited in NCBI GenBank (Accession No. KC993832). The 16S rDNA gene sequence from this phytoplasma was 99% similar to Jujube witches broom phytoplasma (JQ675716), Puna chicory flat stem phytoplasma (JN582266), Plum yellows phytoplasma (FJ459914), and other elm yellows group phytoplasmas by BLAST search of the NCBI database. Restriction fragment length polymorphism (RFLP) analyses were carried out by digesting the 1.2-kb R16F2n/R16R2 nested PCR product with restriction enzymes AluI, RsaI, HhaI, HpaI, Eco RI, TaqI, HaeIII, HinfI, and KpnI (Takara, Dalian). The 16S rDNA RFLP patterns matched that of Jujube witches broom phytoplasma (JWB, subgroup 16SrV-B) (4). Nucleotide sequences of rose balsam phyllody were analyzed by iPhyClassifier software, which revealed that it had maximum similarity to the reference pattern of 16Sr group V, subgroup B (AB052876). All samples were detected with transmission electron microscopy. The results showed phytoplasma-like cells in phloem sieve element of symptomatic plants, while no phytoplasma-like cells were observed in healthy phloem tissues. The phytoplasma cells ranged from 230 to 470 nm in diameter and were ellipsoidal or orbicular with visible membranes. Combining the RFLP pattern and sequence analysis by iPhyClassifier, we classified the phytoplasma causing rose balsam phyllody into subgroup 16SrV-B. To our knowledge, this is the first report of 16SrV-B group phytoplasmas infecting rose balsam in China. References: (1) Z. N. Li et al. J. Phytopathol. 159:799, 2011. (2) M. A. Saghai-Maroof et al. Proc. Natl. Acad. Sci. 81:8014, 1984. (3) I. M. Lee et al. Phytopathology 83:834, 1993. (4) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.

Production and genetic characterization of interspecific hybrids among Crambe abyssinica, Crambe hispanica and Crambe kralikii

In this paper, interspecific crosses among Crambe abyssinica, Crambe hispanica, and Crambe kralikii were reported. In the C. hispanica x C. abyssinica (H x A) cross, 118 F1 hybrids were produced without embryo rescue, while 5 F1 hybrids were obtained with embryo rescue, when C. hispanica was used as the female parent. In the reciprocal cross (A x H), 232 hybrids were obtained without embryo rescue. From more than 1000 C. kralikii flowers pollinated with pollen grains of C. abyssinica (K x A), only 2 F1 hybrids were obtained with embryo rescue, whereas the reciprocal cross produced no hybrids, even with embryo rescue. The hybrids were confirmed at the morphological, cytological, and molecular levels. In the combinations of A x H and H x A, many BC1 hybrids were obtained without embryo rescue. In contrast, in the K x A cross, only 7 BC1 plants were obtained with embryo rescue, while no seed set was achieved under self-pollination or in backcrosses without embryo rescue. In the H x A F1 hybrids, the pollen stainability was 65.4-86.0%, with an average of 76.9%. In comparison, the pollen viability of hybrids in the reciprocal cross (A x H) ranged from 66.2 to 81.1%, with an average of 75.4%. Fertile pollen grains were not found in the K x A F1 hybrids. All F1 hybrids of the 3 crosses (H x A, A x H, and K x A) had the expected 2n = 75 chromosomes. AFLP analyses indicated that all F1 hybrids and their progenies had typical bands of the parents. These hybrids and progenies are anticipated to be valuable for future C. abyssinica improvement in breeding programs.

Atomic Details of Interfacial Interaction in Gold Nanoparticles Supported on MgO(001)

Atomic-scale imaging using aberration-corrected scanning transmission electron microscopy reveals direct evidence for semicoherent interfacial epitaxy and coordinate-dependent surface contraction for the fcc (001) oriented Au nanoparticles (2-3 nm in diameter), suggesting that their interaction with the substrate is weaker than previously assumed. A significant change in interfacial separation distance from 2.47 ± 0.12 Å for the fcc (001) oriented Au nanoparticles to 3.07 ± 0.11 Å for the fcc (111) oriented Au nanoparticles has also been observed. These results are used to verify the atomistic models generated by the global optimization calculations, which shed further light on the intricate relation between the interfacial energy and the atomic structure of the nanoparticle and their combined effect on the inhomogeneous surface structural relaxation of supported nanoparticles.

Design of a highly sensitive ethanol sensor using a nano-coaxial p-Co3O4/n-TiO2 heterojunction synthesized at low temperature

In this paper, we describe the design, fabrication and gas-sensing tests of nano-coaxial p-Co3O4/n-TiO2 heterojunction. Specifically, uniform TiO2 nanotubular arrays have been assembled by anodization and used as templates for generation of the Co3O4 one-dimensional nanorods. The structure morphology and composition of as-prepared products have been characterized by SEM, XRD, TEM, and XPS. A possible growth mechanism governing the formation of such nano-coaxial heterojunctions is proposed. The TiO2 nanotube sensor shows a normal n-type response to reducing ethanol gas, whereas TiO2-Co3O4 exhibits p-type response with excellent sensing performances. This conversion of sensing behavior can be explained by the formation of p-n heterojunction structures. A possible sensing mechanism is also illustrated, which can provide theoretical guidance for the further development of advanced gas-sensitive materials with p-n heterojunction.

Direct atomic imaging and density functional theory study of the Au24Pd1 cluster catalyst

In this study we report a direct, atomic-resolution imaging of calcined Au24Pd1 clusters supported on multiwall carbon nanotubes by employing aberration-corrected scanning transmission electron microscopy. Using gold atoms as mass standards, we confirm the cluster size to be 25 ± 2, in agreement with the Au24Pd1(SR)18 precursor used in the synthesis. Concurrently, a Density-Functional/Basin-Hopping computational algorithm is employed to locate the low-energy configurations of free Au24Pd1 cluster. Cage structures surrounding a single core atom are found to be favored, with a slight preference for Pd to occupy the core site. The cluster shows a tendency toward elongated arrangements, consistent with experimental data. The degree of electron transfer from the Pd dopant to Au is quantified through a Löwdin charge analysis, suggesting that Pd may act as an electron promoter to the surrounding Au atoms when they are involved in catalytic reactions.

An atomistic view of the interfacial structures of AuRh and AuPd nanorods

In this work we address the challenge of furthering our understanding of the driving forces responsible for the metal-metal interactions in industrially relevant bimetallic nanocatalysts, by taking a comparative approach to the atomic scale characterization of two core-shell nanorod systems (AuPd and AuRh). Using aberration-corrected scanning transmission electron microscopy, we show the existence of a randomly mixed alloy layer some 4-5 atomic layers thick between completely bulk immiscible Au and Rh, which facilitates fully epitaxial overgrowth for the first few atomic layers. In marked contrast in AuPd nanorods, we find atomically sharp segregation resulting in a quasi-epitaxial, strained interface between bulk miscible metals. By comparing the two systems, including molecular dynamics simulations, we are able to gain insights into the factors that may have influenced their structure and chemical ordering, which cannot be explained by the key structural and energetic parameters of either system in isolation, thus demonstrating the advantage of taking a comparative approach to the characterization of complex binary systems. This work highlights the importance of achieving a fundamental understanding of reaction kinetics in realizing the atomically controlled synthesis of bimetallic nanocatalysts.

Effects of Dietary Supplementation with Hainanmycin on Protein Degradation and Populations of Ammonia-producing Bacteria In vitro

An in vitro fermentation was conducted to determine the effects of hainanmycin on protein degradation and populations of ammonia-producing bacteria. The substrates (DM basis) for in vitro fermentation consisted of alfalfa hay (31.7%), Chinese wild rye grass hay (28.3%), ground corn grain (24.5%), soybean meal (15.5%) with a forage: concentrate of 60:40. Treatments were the control (no additive) and hainanmycin supplemented at 0.1 (H0.1), 1 (H1), 10 (H10), and 100 mg/kg (H100) of the substrates. After 24 h of fermentation, the highest addition level of hainanmycin decreased total VFA concentration and increased the final pH. The high addition level of hainanmycin (H1, H10, and H100) reduced (p<0.05) branched-chain VFA concentration, the molar proportion of acetate and butyrate, and ratio of acetate to propionate; and increased the molar proportion of propionate, except that for H1 the in molar proportion of acetate and isobutyrate was not changed (p>0.05). After 24 h of fermentation, H10 and H100 increased (p<0.05) concentrations of peptide nitrogen and AA nitrogen and proteinase activity, and decreased (p<0.05) NH₃-N concentration and deaminase activity compared with control. Peptidase activitives were not affected by hainanmycin. Hainanmycin supplementation only inhibited the growth of Butyrivibrio fibrisolvens, which is one of the species of low deaminative activity. Hainanmycin supplementation also decreased (p<0.05) relative population sizes of hyper-ammonia-producing species, except for H0.1 on Clostridium aminophilum. It was concluded that dietary supplementation with hainanmycin could improve ruminal fermentation and modify protein degradation by changing population size of ammonia-producing bacteria in vitro; and the addition level of 10 mg/kg appeared to achieve the best results.

A selective blocking method to control the overgrowth of Pt on Au nanorods

A method for the preparation of smooth deposits of Pt on Au nanorods is described, involving sequential deposition steps with selective blocking of surface sites that reduces Pt-on-Pt deposition. The Au-Pt nanorods prepared by this method have higher long-term stability than those prepared by standard Pt deposition. Electrochemical data show that the resulting structure has more extended regions of Pt surface and enhanced activity toward the carbon monoxide oxidation and oxygen reduction reactions.

DFT study of the structures and energetics of 98-atom AuPd clusters

The energetics, structures and segregation of 98-atom AuPd nanoclusters are investigated using a genetic algorithm global optimization technique with the Gupta empirical potential (comparing three different potential parameterisations) followed by local minimizations using Density Functional Theory (DFT) calculations. A shell optimization program algorithm is employed in order to study the energetics of the highly symmetric Leary Tetrahedron (LT) structure and optimization of the chemical ordering of a number of structural motifs is carried out using the Basin Hopping Monte Carlo approach. Although one of the empirical potentials is found to favour the LT structure, it is shown that Marks Decahedral and mixed FCC-HCP motifs are lowest in energy at the DFT level.

Ischaemic postconditioning rescues brain injury caused by focal ischaemia/reperfusion via attenuation of protein oxidization

OBJECTIVE

To investigate the effects of ischaemic postconditioning on brain injury and protein oxidization in focal ischaemia/reperfusion.

METHODS

Adult male Wistar rats (n = 30) were randomly divided into sham-operated, ischaemia, and ischaemic postconditioning groups. Ischaemia was produced by middle cerebral artery occlusion and ischaemic postconditioning was performed using three cycles of 30-s/30-s reperfusion/reocclusion after 2 h of ischaemia. Brain infarction size, hydrogen peroxide concentration, superoxide dismutase (SOD), catalase (CAT) and proteasome activities, protein carbonyl derivatives and advanced oxidized protein products (AOPPs) were evaluated.

RESULTS

The size of brain infarction after ischaemic postconditioning was significantly smaller compared with the ischaemia group, and was concomitant with significant reduction in protein carbonyl derivatives and AOPPs. The activities of SOD, CAT and proteasomes were elevated by ischaemic postconditioning compared with the ischaemia group.

CONCLUSIONS

Ischaemic postconditioning is an effective way of reducing the size and effects of brain infarction caused by focal ischaemia/reperfusion, possibly due to a decrease in oxidized protein levels. Decreasing protein oxidization may, therefore, be a useful target for preventing cerebral injury.

Size and shape of nanoclusters: single-shot imaging approach

A method of single-shot imaging via aberration-corrected scanning transmission electron microscopy equipped with high angle annular dark-field detector (STEM-HAADF) has been applied to size-selected gold model catalysts (Au(25) and Au(39) ) on hydroxyapatite. Through quantitative intensity analysis, the size, in terms of number of atoms as well as 3D shape of the clusters are obtained.

First Report of Elm Yellows Subgroup 16SrV-B Phytoplasma Infecting Chinese Tulip Tree in China

Chinese tulip tree (Liriodendron chinensis) is native to China and is planted all around the country as an ornamental tree. In July of 2011, some Chinese tulip trees with typical phytoplasma symptoms were found in Baoding City, Hebei Province, China. Symptoms included yellowing of leaves, slow decline, little leaves, and death of entire plants. To confirm phytoplasma infection of these plants, total DNA was extracted from 100 mg of fresh leaf midribs collected from leaves of nine symptomatic and eight asymptomatic plants with a plant DNA extract kit (Tiangen, Beijing, China) according to the manufacturer's protocols. Using 16S rRNA phytoplasma universal primer pairs P1/P7 followed by R16F2n/R16R2, a nest PCR was carried out (1,2). The results showed that the phytoplasma was only detected in symptomatic samples by nested PCR, while the asymptomatic were negative. An approximate 1.2-kb specific fragment was obtained from the DNA of nine symptomatic plants, but no product was amplified from the leaves of eight healthy ones. The amplified products were cloned and sequenced. The sequence was deposited in GenBank Data Libraries under Accession No. JQ585925 and shared the highest homology of 99% with Puna chicory flat stem phytoplasma (GenBank Accession No. JN582266), Apricot leaf roll phytoplasma (GenBank Accession No. FJ572660), Jujube witches'-broom phytoplasma (GenBank Accession No. AY197661), and other elm yellows group phytoplasmas by BLAST analysis with that of other phytoplasmas from GenBank. Meanwhile, the sequence data was analyzed by iPhyClassifier software and the result showed that the 16S rDNA F2nR2 fragment was identical (similarity coefficient 1.00) to the reference patterns of 16Sr group V, subgroup B (GenBank Accession No.AB052876) (3). Combining the BLAST analysis in GenBank and the analysis of iPhyClassifier, we classified the phytoplasma causing Chinese tulip tree yellow leaves disease into subgroup 16SrV-B. To our knowledge, this is the first report of the 16SrVB group phytoplasmas infecting Chinese tulip tree in China. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) I. M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:337, 2004. (3) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Genome affinity and meiotic behaviour in trigenomic hybrids and their doubled allohexaploids between three cultivated Brassica allotetraploids and Brassica fruticulosa

The wild species Brassica fruticulosa Cyr. (FF, 2n = 16) is closely related to the cultivated Brassica species. Through interspecific reciprocal crosses between B. fruticulosa and three cultivated Brassica allotetraploids (AABB, AACC, and BBCC where A = 10, B = 8, and C = 9), four trigenomic hybrids (F.AC, 2n = 27; F.AB, 2n = 26; F.BC, 2n = 25; BC.F, 2n = 25) were produced. By chromosome doubling of respective hybrids, three allohexaploids (FF.AACC, 2n = 54; FF.AABB, 2n = 52; BBCC.FF, 2n = 50) were synthesized. In pollen mother cells (PMCs) of the trigenomic hybrids, 1–2 autosyndetic bivalents were detected within A, B, and C genomes but only one within F genome; 1–3 allosyndetic bivalents between any two genomes were observed, and a closer relationship of F and B genomes than F and A genomes or F and C genomes was revealed. The allohexaploids showed a generally low but different pollen fertilities. The chromosomes in PMCs were predominantly paired as bivalents but some univalents and multivalents at variable frequencies were observed. The bivalents of homologous pairing for each genome prevailed, but allosyndetic quadrivalents and hexavalents involving any two genomes were observed, together with autosyndetic quadrivalents for A, B, and C genomes but not the F genome. The nondiploidized cytological behaviour of these allohexaploids contributed to their low fertility. The relationships between the genome affinity and meiotic behavior in these allohexaploids were discussed.

Spin-orbit splitting in graphene on metallic substrates

Substrate-induced spin-orbit splitting in graphene on Ni, Au and Ag(111) is examined on the basis of density-functional theory. The Rashba splitting of π bands along the ΓM direction of the graphene surface Brillouin zone in graphene on Ni(111) is found to be very small (a few millielectronvolts), consistent with the experimental report of Rader et al. Instead, very strong Rashba splitting (near 100 meV) can be obtained for graphene with a certain stretch distortion on a Au substrate. It can be ascribed to the effective match in energy between the C 2p and Au 5d bands, obtained from the analysis of densities of states. The net charge transfer between the graphene and the substrates just affects the spin-orbit effect indirectly. The small spin-orbit splitting induced by the Ag substrates indicates that heavy metals do not always produce large SO splitting. Our findings provide important insights that are useful for understanding the metal-induced Rashba effect in graphene.

Energy transfer from InGaN quantum wells to Au nanoclusters via optical waveguiding

We present the first observation of resonance energy transfer from InGaN quantum wells to Au nanoclusters via optical waveguiding. Steady-state and time-resolved photoluminescence measurements provide conclusive evidence of resonance energy transfer and obtain an optimum transfer efficiency of ~72%. A set of rate equations is successfully used to model the kinetics of resonance energy transfer.

Association between biomechanical structural stresses of atherosclerotic carotid plaques and subsequent ischaemic cerebrovascular events--a longitudinal in vivo magnetic resonance imaging-based finite element study

BACKGROUND

High-resolution magnetic resonance (MR) imaging has been used for MR imaging-based structural stress analysis of atherosclerotic plaques. The biomechanical stress profile of stable plaques has been observed to differ from that of unstable plaques; however, the role that structural stresses play in determining plaque vulnerability remains speculative.

METHODS

A total of 61 patients with previous history of symptomatic carotid artery disease underwent carotid plaque MR imaging. Plaque components of the index artery such as fibrous tissue, lipid content and plaque haemorrhage (PH) were delineated and used for finite element analysis-based maximum structural stress (M-C Stress) quantification. These patients were followed up for 2 years. The clinical end point was occurrence of an ischaemic cerebrovascular event. The association of the time to the clinical end point with plaque morphology and M-C Stress was analysed.

RESULTS

During a median follow-up duration of 514 days, 20% of patients (n = 12) experienced an ischaemic event in the territory of the index carotid artery. Cox regression analysis indicated that M-C Stress (hazard ratio (HR): 12.98 (95% confidence interval (CI): 1.32-26.67, p = 0.02), fibrous cap (FC) disruption (HR: 7.39 (95% CI: 1.61-33.82), p = 0.009) and PH (HR: 5.85 (95% CI: 1.27-26.77), p = 0.02) are associated with the development of subsequent cerebrovascular events. Plaques associated with future events had higher M-C Stress than those which had remained asymptomatic (median (interquartile range, IQR): 330 kPa (229-494) vs. 254 kPa (166-290), p = 0.04).

CONCLUSIONS

High biomechanical structural stresses, in addition to FC rupture and PH, are associated with subsequent cerebrovascular events.

Formation and identification of interfacial-active glycolipids from resting microbial cells

Resting cells of Arthrobacter sp. strain DSM2567 incubated in the presence of various mono-, di-, or trisaccharides biosynthesized different glycolipids. All eight glycolipids, containing the corresponding carbohydrate moiety and one, two, or three alpha-branched beta-hydroxy fatty acids, were produced when mannose, glucose, cellobiose, maltose, and maltotriose were used as carbon sources in a simple phosphate buffer. The structures of the compounds were elucidated by means of H and C nuclear magnetic resonance spectroscopy and by chemical ionization mass spectroscopy. In high-salinity solution, the substances showed different surfactant properties. Cellobiose and maltose monocorynomycolates reduced the interfacial tension from 42 to 1 mN/m at critical micelle concentrations below 20 mg/liter.

Intra- and intergenomic chromosome pairings revealed by dual-color GISH in trigenomic hybrids of Brassica juncea and B. carinata with B. maurorum

From dual-color genomic in situ hybridization (GISH) analysis of three trigenomic hybrids, Brassica maurorum (MM, 2n = 16) x B. juncea (AABB, 2n = 36) (M.AB), B. maurorum x B. carinata (BBCC, 2n = 34) (M.BC), and B. carinata x B. maurorum (BC.M), the three genomes of each hybrid were distinguished and autosyndesis and allosyndesis were evaluated. In M.AB, up to two autosyndetic bivalents occurred among the chromosomes of each genome; a maximum of three allosyndetic bivalents appeared between A-B, A-M, and B-M genomes. The similar pairings in M.BC and BC.M suggested that the cytoplasm of B. maurorum or B. carinata had no obvious effect on chromosome pairing. In M.BC and BC.M, a maximum of one autosyndetic bivalent was found for B and M genomes, but two were found for the C genome; from 0 to 2 allosyndetic bivalents were observed between B-C, B-M, and C-M genomes. The B-M allosyndesis frequency was higher than the A-M or C-M allosyndesis frequency in these hybrids, revealing the closer relationship of B and M genomes. The allosyndesis frequency was higher than the autosyndesis frequency among A, B, and C genomes in these combinations, suggesting that intergenomic homoeology was higher than intragenomic homoeology. The implications for genome evolution and crop breeding are discussed.

First Report of Impatiens necrotic spot virus on Spiderlily in China

Impatiens necrotic spot virus (INSV) (genus Tospovirus; family Bunyaviridae) is a devastating disease in the production of ornamental flowers (1). From 2007 to 2009, a survey of 10 major parks and recreation areas in Kunming, the capital of Yunnan Province, China, indicated that approximately 60 to 70% of Spiderlily (Hymenocallis littoralis Salisb.) plants from eight parks had symptoms of concentric ring spots and necrotic spots. Symptomatic plants were tested for INSV and Tomato spotted wilt virus (TSWV) with an immunostrip (Agdia Inc. Elkhart, IN). Results indicated that only the samples designated HDL were positive for INSV and all other samples were negative for both INSV and TSWV. Mechanically inoculated Emilia sonchifolia, Nicotiana glutinosa, Impatiens balsamina, and N. rustica showed chlorotic lesions, concentric rings, and severe necrosis, symptoms typical for INSV in these hosts. Electron microscope inspection found tospovirus-like spheroidal, enveloped particles that were 90 nm in diameter. Primer 5 software (Premier, Canada) was used to design 14 primers from GenBank Accession No. NC_003625 to amplify the L RNA, nine from NC_003616 to amplify the M RNA, and six from NC_003624 to amplify the S RNA. With total RNA extracted from infected plant tissue as templates in reverse transcription (RT)-PCR, these primers generated 29 target fragments of 250 to 900 bp. These fragments were cloned with the vector pMD19 simple-T vector (Takara Bio Inc., Dalian, China) and sequenced. The sequences of the clones were aligned with the software DNAman (version 2.5; Lynnon Biosoft, Quebec, Canada), showing that RNAs L, M, and S are 8,776 bp (GenBank Accession No. GU112505), 4,948 bp (GenBank Accession No. GU112503), and 2,875 bp (GenBank Accession No. GU112504), respectively. BLAST analysis of these Spiderlily INSV sequences against the NCBI sequence database indicated that the RdRp protein (L RNA) was 99.6% identical with the RdRp protein from an Italian isolate (No. DQ425094), the Nsm protein (M RNA) has 99.0% identity with the Nsm protein from an isolate from Italy (No. DQ425095) and one from the United States (No. NC_003616), the G1G2 polyprotein (M RNA) has 99.9% identity with the analogous protein from an Italian isolate (No. DQ425095), the N protein (S RNA) has 99.6% identity with the N protein from an Italian isolate (No. DQ425096), and the NSs protein (S RNA) has 98.7% identity with the NSs protein from an isolate from Japan (No. AB109100). To our knowledge, this is the first report of INSV on Spiderlily in China. Reference: (1) A. E. Whitfield et al. Annu. Rev. Phytopathol. 43:459, 2005.

Quantum transport in alkane molecular wires: effects of binding modes and anchoring groups

Effects of binding modes and anchoring groups on nonequilibrium electronic transport properties of alkane molecular wires are investigated from atomic first-principles based on density functional theory and nonequilibrium Green's function formalism. Four typical binding modes, top, bridge, hcp-hollow, and fcc-hollow, are considered at one of the two contacts. For wires with three different anchoring groups, dithiol, diamine, or dicarboxylic acid, the low bias conductances resulting from the four binding modes are all found to have either a high or a low value, well consistent with recent experimental observations. The trend can be rationalized by the behavior of electrode-induced gap states at small bias. When bias increases to higher values, states from the anchoring groups enter into the bias window and contribute significantly to the tunneling process so that transport properties become more complicated for the four binding modes. Other low bias behaviors including the values of the inverse length scale for tunneling characteristic, contact resistance, and the ratios of the high/low conductance values are also calculated and compared to experimental results. The conducting capabilities of the three anchoring groups are found to decrease from dithiol, diamine to dicarboxylic-acid, largely owing to a decrease in binding strength to the electrodes. Our results give a clear microscopic picture to the transport physics and provide reasonable qualitative explanations for the corresponding experimental data.

Strontium borate glass: potential biomaterial for bone regeneration

Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones.

Invasive and non-invasive modalities of imaging carotid stenosis

Despite recent therapeutic advances, acute ischemic complications of atherosclerosis remain the primary cause of morbidity and mortality in Western countries, with carotid atherosclerotic disease one of the major preventable causes of stroke. As the impact of this disease challenges our healthcare systems, we are becoming aware that factors influencing this disease are more complex than previously realized. In current clinical practice, risk stratification relies primarily on evaluation of the degree of luminal stenosis and patient symptomatology. Adequate investigation and optimal imaging are important factors that affect the quality of a carotid endarterectomy (CEA) service and are fundamental to patient selection. Digital subtraction angiography is still perceived as the most accurate imaging modality for carotid stenosis and historically has been the cornerstone of most of the major CEA trials but concerns regarding potential neurological complications have generated substantial interest in non-invasive modalities, such as contrast-enhanced magnetic resonance angiography. The purpose of this review is to give an overview to the vascular specialist of the current imaging modalities in clinical practice to identify patients with carotid stenosis. Advantages and disadvantages of each technique are outlined. Finally, limitations of assessing luminal stenosis in general are discussed. This article will not cover imaging of carotid atheroma morphology, function and other emerging imaging modalities of assessing plaque risk, which look beyond simple luminal measurements.

Electrically controlled optical Tamm states in magnetophotonic crystal based on nematic liquid crystals

A tunable optical Tamm state is investigated in a magnetophotonic crystal with nematic liquid crystals. It is revealed that the intra-Brillouin-zone bandgaps exist and clearly depend on the applied voltages. We find that the optical Tamm state does occur at the boundary between two photonic crystals, one of which is composed of two dielectric materials and the other that consists of a nematic liquid crystal and a magnetic material. A shift of the optical Tamm state with the applied voltage, which stems from the change in the dielectric permittivity of the nematic liquid crystal, is observed. This novel scheme offers a possibility of controlling the optical Tamm state in magnetophotonic crystals induced by nematic liquid crystals.

Structures and energetics of indium-catalyzed silicon nanowires

Strong size dependent structures of Si nanowires, grown via indium nanoparticles, have been revealed by high-resolution transmission electron microscopy studies. It is found that, below the critical value of particle diameter of approximately 100 nm, the growth changes from 111 to predominantly 211 direction and the formation of multiple {111} twins changes from perpendicular to the 111 growth direction to parallel to the 211 axial direction. The growth mechanisms are discussed in terms of relative surface/interface energy, using Au catalyzed Si nanowires as a comparative benchmark.

Extracellular matrix stability of primary mammalian chondrocytes and intervertebral disc cells cultured in alginate-based microbead hydrogels

Three-dimensional alginate constructs are widely used as carrier systems for transplantable cells. In the present study, we evaluated the chondrogenic matrix stability of primary rat chondrocytes and intervertebral disc (IVD) cells cultured in three different alginate-based microbead matrices to determine the influence of microenvironment on the cellular and metabolic behaviors of chondrogenic cells confined in alginate microbeads. Cells entrapped in calcium, strontium, or barium ion gelled microbeads were monitored with the live/dead dual fluorescent cell viability assay kit and the 1,9-dimethylmethylene blue (DMB) assay designed to evaluate sulfated glycosaminoglycan (s-GAG) production. Expression of chondrogenic extracellular matrix (ECM) synthesis was further evaluated by semiquantitative RT-PCR of sox9, type II collagen, and aggrecan mRNAs. Results indicate that Ca and Sr alginate maintained significantly higher population of living cells compared to Ba alginate (p < 0.05). Production of s-GAG was similarly higher in Ca and Sr alginate microbead cultures compared to Ba alginate microbeads. Although there was no significant difference between strontium and calcium up to day 14 of culture, Sr alginate showed remarkably improved cellular and metabolic activities on long-term cultures, with chondrocytes expressing as much as 31% and 44% greater s-GAG compared to calcium and barium constructs, respectively, while IVD cells expressed 63% and 74% greater s-GAG compared to calcium and barium constructs, respectively, on day 28. These findings indicate that Sr alginate represent a significant improvement over Ca- and Ba alginate microbeads for the maintenance of chondrogenic phenotype of primary chondrocytes and IVD cells.

Voltage-controlled Kerr effect in magnetophotonic crystal

A magneto-optical tunable device based on a one-dimensional magnetophotonic crystal infiltrated with a nematic liquid crystal has been proposed. By applying a tunable electric field the voltage-induced reorientation of the director results in an alternating magneto-optical effect. The transfer matrix method was performed to verify the controllable magneto-optical properties. The present results may be useful for future application of liquid crystal-based tunable magneto-optical devices.

Weighing supported nanoparticles: size-selected clusters as mass standards in nanometrology

We present a new approach to quantify the mass and 3D shape of nanoparticles on supports, using size-selected nanoclusters as mass standards in scanning transmission electron microscope. Through quantitative image intensity analysis, we show that the integrated high angle annular dark field intensities of size-selected gold clusters soft-landed on graphite display a monotonic dependence on the cluster size as far as approximately 6500 atoms. We applied this mass standard to study gold nanoparticles prepared by thermal vapor deposition and by colloidal wet chemistry, and from which we deduced the shapes of these two types of nanoparticles as expected.

Osteogenic behavior of alginate encapsulated bone marrow stromal cells: an in vitro study

Sodium alginate is a useful polymer for the encapsulation and immobilization of a variety of cells in tissue engineering because it is biocompatible, biodegradable and easy to process into injectable microbeads. Despite these properties, little is known of the efficacy of calcium cross-linked alginate gel beads as a biodegradable scaffold for osteogenic cell proliferation and differentiation. In this study, we investigated the ability of rabbit derived bone marrow cells (BMCs) to proliferate and differentiate in alginate microbeads and compared them with BMCs cultured in poly-L-lysine (PLL) coated microbeads and on conventional 2D plastic surfaces. Results show that levels of proliferation and differentiation in microbeads and on tissue culture plastics were comparable. Cell proliferation in microbeads however diminished after fortification with a coating layer of PLL. Maximum cell numbers observed were, 3.32 x 10(5) +/- 1.72 x 103; 3.11 x 10(5) +/- 1.52 x 10(3) and 3.28 x 10(5) +/- 1.21 x 10(3 ) for the uncoated, PLL coated and plastic surface groups respectively. Alkaline phosphatase and protein expressions reflected the stage of cell differentiation. We conclude that calcium cross-linked alginate microbeads can act as a scaffold for BMC proliferation and osteogenic differentiation and has potential for use as 3D degradable scaffold.

Combined PET-FDG and USPIO-enhanced MR imaging in patients with symptomatic moderate carotid artery stenosis

INTRODUCTION

PET-FDG and USPIO-enhanced MRI are increasingly being used in depicting carotid atheroma inflammation--a risk factor for the high risk plaque. Their combined use has not been previously reported.

REPORT

Two patients presenting with stroke and identified with 50% carotid stenosis on duplex ultrasonography, underwent PET FDG and USPIO-enhanced MR imaging. Results were concordant and complementary suggesting that both techniques reflect similar metabolic processes.

DISCUSSION

The selection of patients for carotid revascularisation has largely been based on the severity of luminal stenosis alone. The two imaging modalities, which identify inflammatory activity, may be potential surrogate risk markers in the selection of patients eligible for carotid surgery, if plaque inflammation can be correlated with risk of developing clinical symptoms.

Stereo and enantioselective degradation of beta-Cypermethrin and beta-Cyfluthrin in soil

beta-Cypermethrin (beta-CP) and beta-Cyfluthrin (beta-CF) are two important pyrethroid insecticides and both consist of two enantiomeric pairs (diastereomers), i.e. four enantiomers. In this study, the stereo and enantioselective degradation of beta-CP and beta-CF in a Tianjin alkaline soil was studied in details by a combination of achiral and chiral HPLC. The results showed that for the two pyrethroids, the transdiastereomer was degraded faster than the corresponding cis-diastereomer. beta-CP and beta-CF were found to be configurationally unstable in this soil, since isomerization between diastereomers was observed during the degradation process. Further enantioselective analysis showed that significant enantioselectivity occurred during the 30 days incubation time. The enantiomeric ratio (ER) values of cis- and transdiastereomers changed from initial approximately 1.00 to final 0.79 and 0.55 for beta-CP, and to 0.64 and 0.48 for beta-CF, respectively. At last, it was found that beta-CF was degraded at relatively faster degradation rate and higher enantioselectivity than beta-CP. Findings from this study may be used to better understand the chiral profiles of beta-CP and beta-CF as well as relevant pyrethroid analogues in environment.

High-resolution detection of Au catalyst atoms in Si nanowires

The potential for the metal nanocatalyst to contaminate vapour-liquid-solid grown semiconductor nanowires has been a long-standing concern, because the most common catalyst material, Au, is highly detrimental to the performance of minority carrier electronic devices. We have detected single Au atoms in Si nanowires grown using Au nanocatalyst particles in a vapour-liquid-solid process. Using high-angle annular dark-field scanning transmission electron microscopy, Au atoms were observed in higher numbers than expected from a simple extrapolation of the bulk solubility to the low growth temperature. Direct measurements of the minority carrier diffusion length versus nanowire diameter, however, demonstrate that surface recombination controls minority carrier transport in as-grown n-type nanowires; the influence of Au is negligible. These results advance the quantitative correlation of atomic-scale structure with the properties of nanomaterials and can provide essential guidance to the development of nanowire-based device technologies.

Correlation of carotid atheromatous plaque inflammation with biomechanical stress: Utility of USPIO enhanced MR imaging and finite element analysis

OBJECTIVE

The aim of this study was to explore whether there is a relationship between the degree of MR-defined inflammation using ultra small super-paramagnetic iron oxide (USPIO) particles, and biomechanical stress using finite element analysis (FEA) techniques, in carotid atheromatous plaques.

METHODS AND RESULTS

18 patients with angiographically proven carotid stenoses underwent multi-sequence MR imaging before and 36 h after USPIO infusion. T(2)(*) weighted images were manually segmented into quadrants and the signal change in each quadrant normalised to adjacent muscle was calculated after USPIO administration. Plaque geometry was obtained from the rest of the multi-sequence dataset and used within a FEA model to predict maximal stress concentration within each slice. Subsequently, a new statistical model was developed to explicitly investigate the form of the relationship between biomechanical stress and signal change. The Spearman's rank correlation coefficient for USPIO enhanced signal change and maximal biomechanical stress was -0.60 (p=0.009).

CONCLUSIONS

There is an association between biomechanical stress and USPIO enhanced MR-defined inflammation within carotid atheroma, both known risk factors for plaque vulnerability. This underlines the complex interaction between physiological processes and biomechanical mechanisms in the development of carotid atheroma. However, this is preliminary data that will need validation in a larger cohort of patients.

Comparison of the inflammatory burden of truly asymptomatic carotid atheroma with atherosclerotic plaques in patients with asymptomatic carotid stenosis undergoing coronary artery bypass grafting: an ultrasmall superparamagnetic iron oxide enhanced magnetic resonance study

INTRODUCTION

Inflammation is a recognized risk factor for the vulnerable atherosclerotic plaque. The aim of this study was to explore whether there is a difference in the degree of Magnetic Resonance (MR) defined inflammation using Ultra Small Super-Paramagnetic Iron Oxide (USPIO) particles, within carotid atheroma in completely asymptomatic individuals and the asymptomatic carotid stenosis in a cohort of patients undergoing coronary artery bypass grafting (CABG).

METHODS

10 patients awaiting CABG with asymptomatic carotid disease and 10 completely asymptomatic individuals with no documented coronary artery disease underwent multi-sequence MR imaging before and 36 hours post USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant, normalised to adjacent muscle signal, was calculated following USPIO administration.

RESULTS

The mean percentage of quadrants showing signal loss was 94% in the CABG group, compared to 24% in the completely asymptomatic individuals (p<0.001). The carotid plaques from the CABG patients showed a significant mean signal intensity decrease of 16.4% after USPIO infusion (95% CI 10.6% to 22.2%; p<0.001). The truly asymptomatic plaques showed a mean signal intensity increase (i.e. enhancement) after USPIO infusion of 8.4% (95% CI 2.6% to 14.2%; p=0.007). The mean signal difference between the two groups was 24.9% (95% CI 16.7% to 33.0%; p<0.001).

CONCLUSIONS

These findings are consistent with the hypothesis that inflammatory atheroma is a systemic disease. The carotid territory is more likely to take up USPIO if another vascular territory is symptomatic.

Characteristics and mechanical properties of acrylolpamidronate-treated strontium containing bioactive bone cement

The aim of the present study was to determine the influence of surface treatment on the mechanical properties of strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement. Previously we developed an injectable bioactive cement (SrHAC) system composed of Sr-HA powders and bisphenol A diglycidylether dimethacrylate (Bis-GMA). In this study, the Sr-HA powder was subjected to surface treatment using acrylolpamidronate, a bisphosphonate derivative, which has a polymerizable group, to improve the interface between inorganic filler and organic matrix by binding Sr-HA and copolymerizing into the matrix. After surface treatment, the compression strength, bending strength, and stiffness of the resulting composites were defined by using a material testing machine (MTS) according to ISO 5833. The fracture surface of the bone cement specimen was observed with a scanning electron microscope. Invitro cytotoxicity of surface-treated SrHAC was also studied using a tetrazolium-based cell viability assay (MTS/pms) on human osteoblast-like cells, the SaOS-2 cell line. Cells were seeded at a density of 10(4)/mL and allowed to grow in an incubator for 48 h at 37 degrees C. Results indicated that after surface treatment, the compression strength and stiffness significantly improved by 22.68 and 14.51%, respectively. The bending strength and stiffness of the bioactive bone cement also showed 19.06 and 8.91% improvements via three-point bending test. The fracture surface micromorphology after compression and bending revealed that the bonding between the resin to surface-treated filler considerably improved. The cell viability indicated that the treated particles were nontoxic and did not inhibit cell growth. This study demonstrated a new surface chemistry route to enhance the covalent bonds between inorganic fillers and polymer matrix for improving the mechanical properties of bone cement. This method not only improves the overall mechanical performance but also increases osteoblastic activity.

Effect of weight-bearing on bone-bonding behavior of strontium-containing hydroxyapatite bone cement

The purpose of this study was to investigate and compare the chemical composition and nanomechanical properties at the bone-cement interface under non-weight-bearing and weight-bearing conditions, in order to understand the effect of weight-bearing on the bone-bonding behavior of strontium-containing hydroxyapatite (Sr-HA) cement. In one group, Sr-HA cement was injected into rabbit ilium (under non-weight-bearing conditions). Unilateral hip replacement was performed with Sr-HA cement (under weight-bearing conditions) in the other group. Six months later, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis and nanoindentation tests were conducted on the interfaces between cancellous bone and the Sr-HA cement. The nanoindentation results revealed two different transitional behaviors under different conditions. nder weight-bearing conditions, both the Young modulus and hardness at the interface were considerably higher than those at either the Sr-HA cement or cancellous bone. On the contrary, under non-weight-bearing conditions, both the Young modulus and hardness values at the interface were lower than those at the cancellous bone, but were higher than the Sr-HA cement. In addition, EDX results showed that the calcium and phosphorus contents at the interface under weight-bearing conditions were considerably higher than those under non-weight-bearing conditions. The differences in chemical composition and nanomechanical properties at the cement-bone interface under two different conditions indicate that weight-bearing produces significant effects on the bone-bonding behavior of the Sr-HA cement.

Mechanical properties of femoral cortical bone following cemented hip replacement

Femoral bone remodeling following total hip replacement is a big concern and has never been examined mechanically. In this study, six goats underwent unilateral cemented hip hemiarthroplasty with polymethyl methacrylate (PMMA) bone cement. Nine months later animals were sacrificed, and the femoral cortical bone slices at different levels were analysed using microhardness testing and microcomputed tomography (micro-CT) scanning. Implanted femurs were compared to contralateral nonimplanted femurs. Extensive bone remodeling was demonstrated at both the proximal and middle levels, but not at the distal level. Compared with the nonimplanted side, significant decreases were found in the implanted femur in cortical bone area, bone mineral density, and cortical bone hardness at the proximal level, as well as in bone mineral density and bone hardness at the middle level. However, no significant difference was observed in either variable for the distal level. In addition, similar proximal-to-distal gradient changes were revealed both in cortical bone microhardness and bone mineral density. From the mechanical point of view, the results of the present study suggested that stress shielding is an important mechanical factor associated with bone adaptation following total hip replacement.

Chemical composition, crystal size and lattice structural changes after incorporation of strontium into biomimetic apatite

Recently, strontium (Sr) as ranelate compound has become increasingly popular in the treatment of osteoporosis. However, the lattice structure of bone crystal after Sr incorporation is yet to be extensively reported. In this study, we synthesized strontium-substituted hydroxyapatite (Sr-HA) with different Sr content (0.3%, 1.5% and 15% Sr-HA in mole ratio) to simulate bone crystals incorporated with Sr. The changes in chemical composition and lattice structure of apetite after synthetic incorporation of Sr were evaluated to gain insight into bone crystal changes after incorporation of Sr. X-ray diffraction (XRD) patterns revealed that 0.3% and 1.5% Sr-HA exhibited single phase spectrum, which was similar to that of HA. However, 15% Sr-HA induced the incorporation of HPO4(2-) and more CO3(2-), the crystallinity reduced dramatically. Transmission electron microscopy (TEM) images showed that the crystal length and width of 0.3% and 1.5% Sr-HA increased slightly. Meanwhile, the length and width distribution were broadened and the aspect ratio decreased from 10.68+/-4.00 to 7.28+/-2.80. The crystal size and crystallinity of 15% Sr-HA dropped rapidly, which may suggest that the fundamental crystal structure is changed. The findings from this work indicate that current clinical dosage which usually results in Sr incorporation of below 1.5% may not change chemical composition and lattice structure of bone, while it will broaden the bone crystal size distribution and strengthen the bone.

Double spectral theorem and two type magnitude-squared coherence functions

Studying frequency domain representation for the coherence between two signals is an important basic theoretical problem in the fundamental theories of signal processing. However, the old magnitude-squared coherence function (OMSCF) has been proved identical to 1, so that to cannot be used to extract any coherence information. Here, we will prove a core theorem in frequency domain coherence theories in signal processing, called as the double spectral theorem (DST). Based on the theorem, we presented the two types of new magnitude-squared coherence functions (MSCFs), called as the same type magnitude-squared coherence function (SMSCF) and the difference magnitude-squared coherence function (DMSCF) respectively, which were mathematically derived from DST and the conditions that they are equal to 1 or 0 can be theoretically derived from DST. Here, we further demonstrated that SMSCF and DMSCF could be used to exactly extract the coherence between two signals by each component.

Using independent component analysis to research heart rate variability

Independent component analysis (ICA) and neural networks were used to extract sub-signals of heart rate variability (HRV). Electrocardiogram (ECG) recording was consisted of six minutes when the volunteer was lying and another six minutes when the volunteer was standing. HRV was extracted from ECG. According to time-delay, HRV was divided into five groups as mixed signals. ICA and neural networks reconstructed five signals into two groups. Results showed that one group signal component centralized in low frequency (called IC1); the other did in high frequency (called IC2). The power of IC1 was significantly increased (P<0.05) and the ratio of IC1 to total power was significantly increased (P<0.01) from lying to standing. Comparing the two postural results, it shows that IC1 may express sympathetic activity, and IC2 represents parasympathetic activity. Sympathetic and parasympathetic nervous function can be evaluated respectively and quantificationally by data and graphs from the two decomposed components. Key word: Neural networks, Independent component analysis, Heart rate variability, Autonomic nervous system.

Association of beta-adrenoceptor single nucleotide polymorphisms with resting heart rate

The association of beta-adrenoceptor (B-AR, including three subgroups: Beta1, Beta2 and Beta3) single nucleotide polymorphisms (SNP) with resting heart rate (RHR) were analyzed. RHR of 107 healthy subjects in the supine were detected by computerized system for 8 minutes. Genotyping SNPs of S/G49 and R/G389 of Beta1-AR and W/R64 of Beta3-AR in these subjects were by means of PCR-restriction fragment length polymorphism (PCR-RFLP) technique. Genotyping SNPs of R/G16 and Q/E27 of Beta1-adrenoceptor in these subjects were by means of allele specific primer-PCR (ASP-PCR) technique. It was found that there was no significant difference among RHRs corresponding above SNPs of B-AR, but the SNP of R/G389 of Beta1-AR, in which there was significant difference among RHRs (P<0.05). Either in the female individuals or in the male, those with Beta1-AR G/G389 genotype had the highest RHR. The females with R/R389 genotype had the lowest RHR, however, the males with R/G389 genotype had the lowest RHR. The RHR was not only associated with R/G389 polymorphism of Beta1-adrenoceptor gene significantly, but also was associated with gender in Chinese.

Interfacial behaviour of strontium-containing hydroxyapatite cement with cancellous and cortical bone

The bone-bonding behaviors of various biomaterials have been extensively investigated. However, the precise mechanisms of bone bonding have not yet been clarified, and the differences in interfacial behaviors of biomaterial bonding with cancellous bone and cortical bone have not yet been understood. In this study, strontium-containing hydroxyapatite (Sr-HA) cement, in which 10% calcium ions were substituted by strontium, was performed in a rabbit hip replacement model. Six months later, the morphology and chemical composition of interfaces between Sr-HA cement with cancellous bone and cortical bone were evaluated by field emission scanning electron microscopy (FESEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Remarkable differences between these two interfaces were suggested both in morphology and chemical compositions. An apatite layer was found between Sr-HA cement and cancellous bone with a thickness of about 70 microm. However, only a very thin interface (about 1 microm) was formed with cortical bone. As for the cancellous bone/cement interface, high ions intensity of Ca, P, Sr, Na, and O were confirmed by FESEM-EDX and ToF-SIMS. Differences in morphology and chemical component between these two interfaces provided convincing evidences for the proposed dissolution-precipitation coupling mechanism in the formation of biological apatite.

In vitro evaluation of alginate encapsulated adipose-tissue stromal cells for use as injectable bone graft substitute

This study aims to investigate the survival and osteogenic behavior of murine-derived adipose-tissue stromal cells (ATSCs) encapsulated in alginate microcapsules thereby instigating further studies in this cell delivery strategy for in vivo osteogenesis. Cell viability was quantified using a tetrazolium-based assay and osteogenic differentiation was evaluated by both alkaline-phosphatase (ALP) histochemistry and osteocalcin mRNA analysis. Following microencapsulation, cell numbers increased from 3.9 x 10(3) on day 1 to 7.8 x 10(3) on day 7 and maintained excellent viability in the course of 21-day culture. ALP was 6.9, 5.5, and 3.2 times higher than monolayer cultures on days 7, 14, and 21, respectively. In addition, osteocalcin mRNA was detectable in encapsulated cultures earlier (day 14) than monolayer cultures. We conclude that alginate microcapsules can act as three-dimensional matrix for ATSC proliferation and has potential for use as injectable, biodegradable scaffold in bone tissue engineering.

Strontium-containing hydroxyapatite bioactive bone cement in revision hip arthroplasty

Clinical outcome of cemented implants to revision total hip replacement (THR) is not as satisfactory as primary THR, due to the loss of bone stock and normal trabecular pattern. This study evaluated a bioactive bone cement, strontium-containing hydroxyapatite (Sr-HA) bone cement, in a goat revision hip hemi-arthroplasty model, and compared outcomes with polymethylmethacrylate (PMMA) bone cement. Nine months after operation, significantly higher bonding strength was found in the Sr-HA group (3.36+/-1.84 MPa) than in the PMMA bone cement group (1.23+/-0.73 MPa). After detached from the femoral component, the surface of PMMA bone cement mantle was shown relatively smooth, whereas the surface of the Sr-HA bioactive bone cement mantle was uneven, by SEM observation. EDX analysis detected little calcium and no phosphorus on the surface of PMMA bone cement mantle, while high content of calcium (14.03%) and phosphorus (10.37%) was found on the surface of the Sr-HA bone cement mantle. Even higher content of calcium (17.37%) and phosphorus (10.84%) were detected in the concave area. Intimate contact between Sr-HA bioactive bone cement and bone was demonstrated by histological and SEM observation. New bone bonded to the surface of Sr-HA cement and grew along its surface. However, fibrous tissue was observed between PMMA bone cement and bone. The results showed good bioactivity of Sr-HA bioactive bone cement in this revision hip replacement model using goats. This in vivo study also suggested that Sr-HA bioactive bone cement was superior to PMMA bone cement in terms of bone-bonding strength. Use of bioactive bone cement may be a possible solution overcoming problems associated with the use of PMMA bone cement in revision hip replacement.

Evaluation of adenovirus vectors containing serotype 35 fibers for tumor targeting

There is growing evidence from in vitro studies that subgroup B adenoviruses (Ad) can overcome the limitations in safety and tumor transduction efficiency seen with commonly used subgroup C serotype 5-based vectors. In this study, we confirm that the expression level of the B-group Ad receptor, CD46, correlates with the grade of malignancy of cervical cancer in situ. We also demonstrate the in vivo properties of Ad5-based vectors that contain the B-group Ad serotype 35 fiber (Ad5/35) in transgenic mice that express CD46 in a pattern and at a level similar to humans. Upon intravenous and intraperitoneal injection, an Ad5/35 vector did not efficiently transduce normal tissue, but was able to target metastatic or intraperitoneal tumors that express CD46 at levels comparable to human tumors. When an oncolytic Ad5/35-based vector was employed, in both tumor models antitumor effects were observed. Furthermore, injection of Ad5/35 vectors into CD46 transgenic mice caused less innate toxicity than Ad5 vectors. Our data demonstrate that Ad vectors that target CD46 offer advantages over Ad5-based vectors for treatment of cancer.