Nanoscale imaging of RNA with expansion microscopy

The ability to image RNA identity and location with nanoscale precision in intact tissues is of great interest for defining cell types and states in normal and pathological biological settings. Here, we present a strategy for expansion microscopy of RNA. We developed a small-molecule linker that enables RNA to be covalently attached to a swellable polyelectrolyte gel synthesized throughout a biological specimen. Then, postexpansion, fluorescent in situ hybridization (FISH) imaging of RNA can be performed with high yield and specificity as well as single-molecule precision in both cultured cells and intact brain tissue. Expansion FISH (ExFISH) separates RNAs and supports amplification of single-molecule signals (i.e., via hybridization chain reaction) as well as multiplexed RNA FISH readout. ExFISH thus enables super-resolution imaging of RNA structure and location with diffraction-limited microscopes in thick specimens, such as intact brain tissue and other tissues of importance to biology and medicine.

Hybrid Microscopy: Enabling Inexpensive High-Performance Imaging through Combined Physical and Optical Magnifications

To date, much effort has been expended on making high-performance microscopes through better instrumentation. Recently, it was discovered that physical magnification of specimens was possible, through a technique called expansion microscopy (ExM), raising the question of whether physical magnification, coupled to inexpensive optics, could together match the performance of high-end optical equipment, at a tiny fraction of the price. Here we show that such "hybrid microscopy" methods--combining physical and optical magnifications--can indeed achieve high performance at low cost. By physically magnifying objects, then imaging them on cheap miniature fluorescence microscopes ("mini-microscopes"), it is possible to image at a resolution comparable to that previously attainable only with benchtop microscopes that present costs orders of magnitude higher. We believe that this unprecedented hybrid technology that combines expansion microscopy, based on physical magnification, and mini-microscopy, relying on conventional optics--a process we refer to as Expansion Mini-Microscopy (ExMM)--is a highly promising alternative method for performing cost-effective, high-resolution imaging of biological samples. With further advancement of the technology, we believe that ExMM will find widespread applications for high-resolution imaging particularly in research and healthcare scenarios in undeveloped countries or remote places.

The Orientations of Large Aspect-Ratio Coiled-Coil Proteins Attached to Gold Nanostructures

Methods for patterning biomolecules on a substrate at the single molecule level have been studied as a route to sensors with single-molecular sensitivity or as a way to probe biological phenomena at the single-molecule level. However, the arrangement and orientation of single biomolecules on substrates has been less investigated. Here, the arrangement and orientation of two rod-like coiled-coil proteins, cortexillin and tropomyosin, around patterned gold nanostructures is examined. The high aspect ratio of the coiled coils makes it possible to study their orientations and to pursue a strategy of protein orientation via two-point attachment. The proteins are anchored to the surfaces using thiol groups, and the number of cysteine residues in tropomyosin is varied to test how this variation affects the structure and arrangement of the surface-attached proteins. Molecular dynamics studies are used to interpret the observed positional distributions. Based on initial studies of protein attachment to gold post structures, two 31-nm-long tropomyosin molecules are aligned between the two sidewalls of a trench with a width of 68 nm. Because the approach presented in this study uses one of twenty natural amino acids, this method provides a convenient way to pattern biomolecules on substrates using standard chemistry.

Two-Dimensional Nanoparticle Supracrystals: A Model System for Two-Dimensional Melting

In a Langmuir trough, successive compression cycles can drive a two-dimensional (2D) nanoparticle supracrystal (NPSC) closer to its equilibrium structure. Here, we show a series of equilibrated 2D NPSCs consisting of gold NPs of uniform size, varying solely in the length of their alkanethiol ligands. The ordering of the NPSC is governed by the ligand length, thus providing a model system to investigate the nature of 2D melting in a system of NPs. As the ligand length increases the supracrystal transitions from a crystalline to a liquid-like phase with evidence of a hexatic phase at an intermediate ligand length. The phase change is interpreted as an entropy-driven phenomenon associated with steric constraints between ligand shells. The density of topological defects scales with ligand length, suggesting an equivalence between ligand length and temperature in terms of melting behavior. On the basis of this equivalence, the experimental evidence indicates a two-stage 2D melting of NPSCs.

Three-dimensional nanofabrication by block copolymer self-assembly

Thin films of block copolymers are widely seen as enablers for nanoscale fabrication of semiconductor devices, membranes, and other structures, taking advantage of microphase separation to produce well-organized nanostructures with periods of a few nm and above. However, the inherently three-dimensional structure of block copolymer microdomains could enable them to make 3D devices and structures directly, which could lead to efficient fabrication of complex heterogeneous structures. This article reviews recent progress in developing 3D nanofabrication processes based on block copolymers.

Aligned sub-10-nm block copolymer patterns templated by post arrays

Self-assembly of block copolymer films can generate useful periodic nanopatterns, but the self-assembly needs to be templated to impose long-range order and to control pattern registration with other substrate features. We demonstrate here the fabrication of aligned sub-10-nm line width patterns with a controlled orientation by using lithographically formed post arrays as templates for a 16 kg/mol poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) diblock copolymer. The in-plane orientation of the block copolymer cylinders was controlled by varying the spacing and geometry of the posts, and the results were modeled using 3D self-consistent field theory. This work illustrates how arrays of narrow lines with specific in-plane orientation can be produced, and how the post height and diameter affect the self-assembly.

Assembly of sub-10-nm block copolymer patterns with mixed morphology and period using electron irradiation and solvent annealing

Block copolymer self-assembly generates patterns with periodicity in the ∼10-100 nm range and is increasingly recognized as a route to lithographic patterning beyond the resolution of photolithography. Block copolymers naturally produce periodic patterns with a morphology and length-scale determined by the molecular architecture, and considerable research has been carried out to extend the range of patterns that can be produced from a given block copolymer, but the ability to control the period of the pattern over a wide range and to achieve complex structures with mixed morphologies from a given block copolymer is limited. Here we show how patterns consisting of coexisting sub-10-nm spheres and cylinders and sphere patterns with a range of periods can be created using a combination of serial solvent anneal processes and electron-beam irradiation of selected areas of a film of poly(styrene-block-dimethylsiloxane). These techniques extend the capabilities of block copolymer lithography, enabling complex aperiodic nanoscale patterns to be formed from a single block copolymer thin film.

Highly ordered square arrays from a templated ABC triblock terpolymer

Square-symmetry patterns are of interest in nanolithography but are not easily obtained from self-assembly of a diblock copolymer. Instead, we demonstrate highly ordered 44 nm period square patterns formed in a thin film of polyisoprene-block-polystyrene-block-polyferrocenylsilane (PI-b-PS-b-PFS) triblock terpolymer blended with 15% PS homopolymer by controlling the film thickness, solvent anneal conditions, the surface chemistry and topography of the substrates. The square patterns consist of PFS pillars that remained after removal of the PI and PS with an oxygen plasma. On an unpatterned smooth substrate, the average grain size of the square pattern was increased dramatically to several micrometers by the use of brush layers and specific solvent anneal conditions. Templated self-assembly of well-ordered square patterns was demonstrated on substrates containing nanoscale topographical sidewalls and posts, written by electron beam lithography, in which the sidewalls and base of the substrate were independently chemically functionalized.

Sub-10 nm structures on silicon by thermal dewetting of platinum

A study of the dewetting behavior of platinum-thin-films on silicon was carried out to determine how variation of dewetting parameters affects the evolution of film morphology and to pinpoint which parameters yielded the smallest, most circular features. Platinum film thickness as well as dewetting time and temperature were varied and the film morphology characterized by means of scanning electron microscopy (SEM) analysis. Two different pathways of dewetting predicted in the literature (Vrij 1966 Discuss. Faraday Soc. 42 23, Becker et al 2003 Nat. Mater. 2 59-63) were observed. Depending on the initial criteria, restructuring of the film occurred via hole or droplet formation. With increased annealing time, a transition from an intermediate network structure to separated islands occurred. In addition, the formation of multilayered films, silicide crystals and nanowires occurred for certain parameters. Nevertheless, the dewetting behavior witnessed could be related to physical processes. Droplets with a mean diameter of 9 nm were formed by using a 1.5 nm thick platinum film annealed at 800 °C for 30 s. To demonstrate the suitability of the annealed films for further processing, we then used the dewetted films as masks for reactive ion etching to transfer the pattern into the silicon substrate, forming tapered nanopillars.

Complex self-assembled patterns using sparse commensurate templates with locally varying motifs

Templated self-assembly of block copolymer thin films can generate periodic arrays of microdomains within a sparse template, or complex patterns using 1:1 templates. However, arbitrary pattern generation directed by sparse templates remains elusive. Here, we show that an array of carefully spaced and shaped posts, prepared by electron-beam patterning of an inorganic resist, can be used to template complex patterns in a cylindrical-morphology block copolymer. We use two distinct methods: making the post spacing commensurate with the equilibrium periodicity of the polymer, which controls the orientation of the linear features, and making local changes to the shape or distribution of the posts, which direct the formation of bends, junctions and other aperiodic features in specific locations. The first of these methods permits linear patterns to be directed by a sparse template that occupies only a few percent of the area of the final self-assembled pattern, while the second method can be used to selectively and locally template complex linear patterns.

A path to ultranarrow patterns using self-assembled lithography

The templated self-assembly of block copolymer (BCP) thin films can generate regular arrays of 10-50 nm scale features with good positional and orientational accuracy, but the ordering, registration and pattern transfer of sub-10-nm feature sizes is not well established. Here, we report solvent-annealing and templating methods that enable the formation of highly ordered grating patterns with a line width of 8 nm and period 17 nm from a self-assembled poly(styrene-b-dimethylsiloxane) (PS-PDMS) diblock copolymer. The BCP patterns can be registered hierarchically on a larger-period BCP pattern, which can potentially diversify the available pattern geometries and enables precise pattern registration at small feature sizes. Sub-10-nm-wide tungsten nanowires with excellent order and uniformity were fabricated from the self-assembled patterns using a reactive ion etching process.

ApoEε4 allele is associated with incidental hallucinations and delusions in patients with AD

Of 135 patients with Alzheimer disease (AD), 56 without psychiatric symptoms at the first visit were followed for a mean period of 51.9 +/- 10.3 months to identify incident psychiatric symptoms. The hazard ratios of ApoE epsilon4 allele in developing psychiatric symptoms were calculated by Cox regression hazard analyses. The presence of the ApoE epsilon4 allele carried a 19.0-fold risk for developing hallucinations and a 3.4-fold risk for delusions.

Determinants and distributions of plasma total homocysteine concentrations among school children in Taiwan

BACKGROUND

Plasma total homocysteine (tHcy) level is an independent risk factor for cardiovascular disease (CVD) even among children. The purpose of this study is to evaluate the determinants and distributions of plasma tHcy levels and the relationship between plasma tHcy, folate and vitamin B12 levels among school children in Taipei.

METHODS

After multi-stage sampling, we randomly selected 1234 school children (609 boys and 625 girls) with the mean age of 13 years (from 12 to 15 years) in this study. Fasting plasma tHcy levels were measured using an ABBOTT IMx analyzer (Axis Biochemicals ASA, Oslo, Norway). Plasma folate and vitamin B12 levels were measured by ACS:180 automated chemiluminescence analyzer (Bayer, Tarrytown, NY, USA).

RESULTS

The distribution of plasma tHcy levels were skewed to the right with the mean values of 10.50 and 8.95 micromol/l and medians of 9.67 and 8.474 micromol/l for boys and girls, respectively. Plasma tHcy concentrations were lower in younger children and progressively increased with increasing age. Boys had significantly higher plasma tHcy levels than girls (10.50 +/- 4.134 vs. 8.95 +/- 2.61 micromol/l, p < 0.01) and lower plasma folate levels (6.05 +/- 2.85 vs. 6.39 +/- 2.58 nmol/l, p < 0.01), and vitamin B12 levels (444.8 +/- 158.4 vs. 495.0 +/- 181.5 pmol/l, p < 0.001). Plasma tHcy levels were significantly positively associated with anthropometric measures in boys; but these characteristics attenuated and became insignificant after adjusting for other potential confounders in girls. Plasma tHcy levels were negatively associated with plasma folate and vitamin B12 levels even after adjusting for BMI and other potential confounders in both genders.

CONCLUSIONS

From this study, the distributions of tHcy levels were skewed to the right and the boys had higher plasma tHcy levels than girls. Plasma tHcy levels were significantly positively associated with BMI among boys. Further studies are needed to evaluate the relationship between tHcy and CVD risk factors among children for the better prevention of heart disease in early life.

The effect of surgical stress on insulin sensitivity, glucose effectiveness and acute insulin response to glucose load

Hyperglycemia after stress is a very common clinical phenomenon. It is generally hypothesized that the underlying cause is a neuroendocrine-mediated deterioration in glucose metabolism. However, the detailed roles of insulin sensitivity, glucose effectiveness and acute insulin response to glucose load in response to stress have not been well established. Hernioplasty was used as a minor stress model for studying stress-induced hyperglycemia. Eleven healthy young men were enrolled voluntarily in this study. Their mean age was 22.0 +/- 0.9 yr and BMI 23.3 +/- 0.6 kg/m2. Frequently sampled i.v. glucose tolerance tests were performed one day before and one day after the surgery. Insulin sensitivity (SI), glucose effectiveness (EG) and area under acute insulin response (AIR) were calculated from "minimal model" algorithms. We also measured fasting concentrations of human GH, ACTH and F on the days of the test. Compared to the pre-operation data, levels of ACTH and F did not change significantly after the surgery. Only GH levels were marginally significant. On the other hand, the SI (0.75 +/- 0.1, 0.52 +/- 0.9 x 10(-5) min(-1)/pmol, p = 0.04), EG (0.023 +/- 0.03, 0.016 +/- 0.003 min(-1), p = 0.01) and AIR (6738.5 +/- 1111.6, 5130.0 +/- 1047.2 pmol, p = 0.005) were all significantly decreased after surgery. The percentages of decrease were 16.3 +/- 15.5, 32.1 +/- 10.3 and 17.8 +/- 10.3%, respectively. Finally, only the changes of EG positively correlate with the changes of ACTH before and after surgery. No significant changes were noted among other stress hormones and the changes of SI, EG and AIR. In conclusion, hernioplasty results in reduced SI, EG and AIR. Among them, although not statistically significant, the EG showed the most distinct decrease after the surgery, which has not been found in previous literature.

Spread of 60Co contaminated steel and its legal consequences in Taiwan

Since 1992, over 200 civilian residential and school buildings in Taiwan have been identified to have contained 60Co contaminated steel rebar emitting excessive gamma-radioactivity in living environments. These buildings were mostly constructed in early 1983 and 1984 by employing steels from one steel mill, which had recycled unknown 60Co orphan sources in northern Taiwan. In 1994, a group of residents who once stayed for a protracted period up to 10 y in the contaminated Ming-Sheng Villa filed a civil action against Taiwan's nuclear regulatory office, the Atomic Energy Council, for state tort compensation of 3.4 M U.S. dollars in equivalent. After three years of court processes, the Taipei District Court handed down a decision in partial favor of the exposed residents. Both parties soon appealed against this judgment to the Taiwan Appellate Court. This article analyzes the main legal issues involved, including government's obligations to prevent and eliminate contamination, to take preventive measures, and to take necessary remedial measures; and plaintiffs' assertion on any legal right against governmental offices. Moreover, discussion issues contain the scope of damage and compensation, causation analysis, absence of effective and efficient regulation over radioactive contamination, limit of tort compensation law and compensation amount, weight of medical evidence as well as role of expert witnesses, and related comparative legal studies.

Infrainguinal revascularizations in octogenarians and septuagenarians

OBJECTIVE

Severe atherosclerosis is a major contributor for death in octogenarians and a cause of multiple vascular-related ailments, including claudication and limb loss. Advanced age and health may limit the success of limb-salvaging procedures. Mortality, morbidity, and outcome of infrainguinal grafts have been examined in octogenarians and septuagenarians.

METHODS

After 128 femoropopliteal and 99 femorotibial bypass grafts in 209 octogenarians and 242 femoropopliteal and 166 femorotibial bypass grafts in 383 septuagenarians, survival, primary patency, limb salvage, myocardial infarction and stroke rates were determined. The survival, myocardial infarction, and stroke rates of controls, 1514 octogenarians and 2011 septuagenarians, were compared.

RESULTS

After a bypass graft, 5-year survival of octogenarians (54%) and septuagenarians (64%) was similar (P >.2) and was 89% and 89% for controls. The 5-year primary patency rates were 74% for octogenarians and 68% for septuagenarians (P >.2). Five-year limb salvage rates were 86% for octogenarians and 86% for septuagenarians. After a bypass graft, the respective rates of myocardial infarction were 4.1% and 3.9% per year and of a stroke 3.2% and 3.2% per year for octogenarians and septuagenarians, which occurred more frequently (P <.05) than in controls.

CONCLUSIONS

Death and cardiovascular events are higher after revascularization in octogenarians and septuagenarians, compared with controls, and are related to the severity of atherosclerosis and not age. Patency rates are excellent and similar. Limb salvage procedures should be considered for most octogenarians.

Relationship between single voided urine protein/creatinine ratio and 24-hour urine protein excretion rate among children and adolescents in Taiwan

BACKGROUND

As there have been few studies conducted on children or adolescents, the purpose of this study was evaluate the relationship between single voided urine protein/creatinine (Up/Ucr) ratio and 24-hour urine protein excretion rate (PER), especially among children and adolescents in Taiwan.

METHODS

After multistage random sampling, we collected 1,072 fasting single voided urine samples and 125 24-hour urine samples from seven- to 18-year-old students in Taiwan. We calculated the Up/Ucr of single voided urine samples and the 24-hour PER in urine.

RESULTS

The mean value and the 95th percentile of the fasting single voided urine Up/Ucr ratio were 0.118 and 0.235, respectively. The mean value and the 95th percentile of the 24-hour PER were 3.61 and 5.66 mg/h/m2, respectively. There was no significant difference in Up/Ucr ratio between boys and girls. Up/Ucr ratio decreased significantly as age increased. The fasting single voided Up/Ucr ratio was highly correlated with 24-hour PER, with r2 = 0.95 (p < 0.001).

CONCLUSIONS

Fasting single voided Up/Ucr ratio is a good marker of 24-hour PER. It is also a simple, easy, convenient and speedy method to measure Up excretion. The single voided Up/Ucr ratio may also serve as a reference for the clinical diagnosis of Up excretion among normal subjects.

[Direct optical resolution of acidic biphenyl drugs by high performance liquid chromatography on tris(3,5-dimethylphenylcarbamate) of cellulose]

A chiral stationary phase was prepared by coating cellulose-tris(3, 5-dimethylphenylcarbamate) onto aminopropylated silica gel. A series of enantiomeric acidic biphenyl drugs were directly resolved on the chiral stationary phase (CSP) by normal-phase high performance liquid chromatography (HPLC). A hexane-2-propanol eluting system containing 1% of trifluoroacetic acid was used as mobile phase. Efficient optical resolution of the acidic biphenyl drugs has been attained. The factors that influence chiral discrimination such as structural characeristic of the samples and mobile phase were investigated. An interaction model between the stationary phase and the samples was discussed. The results showed that efficient optical resolution of racemic carboxylic acids could be attained by normal-phase HPLC on CSP using a hexane-2-propanol eluting system containing 1% of trifluoroacetic acid.

[Analysis of imidacloprid and damanlin by high performance liquid chromatography]

A new method for determination of imidacloprid and damanlin by using HPLC was established. It was carried out on a mu Bondapak C18 column (3.9 mm i.d. x 300 mm) with ACN-MeOH-H2O (60:10:30, V/V) as eluent and detected at 240 nm using photodiode array detector. The results of imidacloprid and damanlin were 3.71% and 15.65% respectively. The standard deviations for imidacloprid and damanlin were 0.88% and 0.76% respectively.

Lipoprotein profiles, not anthropometric measures, correlate with serum lipoprotein(a) values in children: the Taipei children heart study

OBJECTIVE

Plasma lipoprotein(a) [Lp(a)] is a risk factor for cardiovascular disease. The purpose of this study is to evaluate the correlation of anthropometric measures, lipids and lipoprotein profiles and serum Lp(a) values among children in Taiwan. We will attempt to find parameters that will be able to predict Lp(a) levels in children.

DESIGN AND METHODS

After a probability-proportional-to size, multi-stages sampling procedure, we randomly sampled 1500 schoolchildren from 10 schools in Taipei city. Anthropometric measures including body weight, body height, waist and hip circumference and skinfolds were measured. We used standard methods to measure serum total cholesterol (CHOL), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), apolipoprotein A1 and B (ApoA1 and ApoB) and Lp(a) levels. We also calculated low density lipoprotein-cholesterol (LDL-C) and CHOL HDL-C ratio (TCHR) by formula.

RESULTS

We sampled 1283 children (635 boys and 648 girls) with a mean age of 13.3 years (from 12 to 16 years) in this study. The mean and medium serum Lp(a) levels were 16.8 and 8.8 mg/dl among boys and 20.8 and 11.9 mg/dl among girls. Children in the highest quintile of Lp(a) (mean = 49.6 and 58.6 mg/dl for boys and girls, respectively) had higher CHOL, LDL-C, ApoB levels and TCHR than children in the lowest quintile (mean = 3.1 and 3.7 mg/dl for boys and girls, respectively). Lipids and lipoprotein profiles, such as CHOL, LDL-C, Apo-B and TCHR were positively correlated with Lp(a) levels in both genders. Furthermore, the children with Lp(a) levels greater than or equal to 30 mg/dl had higher CHOL, LDL-C and Apo-B levels when compared to children with Lp(a) levels less than 30 mg/dl. After adjusting for age, cigarette smoking, alcohol drinking, puberty development and heart rates, LDL-C and ApoB levels were significantly positively associated with Lp(a) levels while ApoA1 was negatively associated among boys. Among girls, only Apo-B was significantly positively associated with Lp(a) and TG was negatively associated with Lp(a) levels. Most importantly, none of the anthropometric measures were significantly correlated with Lp(a) levels.

CONCLUSIONS

From this study, we found that lipids and lipoproteins profiles, rather than degree of adiposity as reflected by anthropometric measures, are significantly associated with serum Lp(a) levels among school children.

Management of Carotid Artery Stenosis: A Review

Carotid endarterectomy clearly benefits high stroke-risk patients, but its value for asymptomatic patients is still being debated. If a high exposure is necessary for redo procedures or distal aneurysms, mandibular subluxation and styloidectomy may be required. Perioperative mortality and morbidity are acceptably low. Restenosis occurs in few patients.http://link.springer-ny.com/link/service/journals/00547/bibs/8n3p139.html