Van der Waals Colloidal Crystals

A general guiding principle for colloidal crystallization is to tame the attractive enthalpy such that it slightly overwhelms the repulsive interaction. As-synthesized colloids are generally designed to retain a strong repulsive potential for the high stability of suspensions, encoding appropriate attractive potentials into colloids has been key to their crystallization. Despite the myriad of interparticle attractions for colloidal crystallization, the van der Waals (vdW) force remains unexplored. Here, it is shown that the implementation of gold cores into silica colloids and the resulting vdW force can reconfigure the pair potential well depth to the optimal range between -1 and -4 kB T at tens of nanometer-scale colloidal distances. As such, colloidal crystals with a distinct liquid gap can be formed, which is evidenced by photonic bandgap-based diffractive colorization.

Strain and crystallographic identification of the helically concaved gap surfaces of chiral nanoparticles

Identifying the three-dimensional (3D) crystal plane and strain-field distributions of nanocrystals is essential for optical, catalytic, and electronic applications. However, it remains a challenge to image concave surfaces of nanoparticles. Here, we develop a methodology for visualizing the 3D information of chiral gold nanoparticles ≈ 200 nm in size with concave gap structures by Bragg coherent X-ray diffraction imaging. The distribution of the high-Miller-index planes constituting the concave chiral gap is precisely determined. The highly strained region adjacent to the chiral gaps is resolved, which was correlated to the 432-symmetric morphology of the nanoparticles and its corresponding plasmonic properties are numerically predicted from the atomically defined structures. This approach can serve as a comprehensive characterization platform for visualizing the 3D crystallographic and strain distributions of nanoparticles with a few hundred nanometers, especially for applications where structural complexity and local heterogeneity are major determinants, as exemplified in plasmonics.

Ultralow-Loss Substrate for Nanophotonic Dark-Field Microscopy

For the colloidal nanophotonic structures, a transmission electron microscope (TEM) grid has been widely used as a substrate of dark-field microscopy because a nanometer-scale feature can be effectively determined by TEM imaging following dark-field microscopic studies. However, an optically lossy carbon layer has been implemented in conventional TEM grids. A broadband scattering from the edges of the TEM grid further restricted an accessible signal-to-noise ratio. Herein, we demonstrate that the freely suspended, ultrathin, and wide-scale transparent nanomembrane can address such challenges. We developed a 1 mm by 600 μm scale and 20 nm thick poly(vinyl formal) nanomembrane, whose area is around 180 times wider than a conventional TEM grid, so that the possible broadband scattering at the edges of the grid was effectively excluded. Also, such nanomembranes can be formed without the assistance of carbon support; allowing us to achieve the highest signal-to-background ratio of scattering among other substrates.

Enantioselective sensing by collective circular dichroism

Quantitative determination and in situ monitoring of molecular chirality at extremely low concentrations is still challenging with simple optics because of the molecular-scale mismatch with the incident light wavelength. Advances in spectroscopy^1-4 and nanophotonics have successfully lowered the detection limit in enantioselective sensing, as it can bring the microscopic chiral characteristics of molecules into the macroscopic scale^5-7 or squeeze the chiral light into the subwavelength scale^8-17. Conventional nanophotonic approaches depend mainly on the optical helicity density^8,9 by localized resonances within an individual structure, such as localized surface plasmon resonances (LSPRs)^10-16 or dielectric Mie resonances¹⁷. These approaches use the local chiral hotspots in the immediate vicinity of the structure, whereas the handedness of these hotspots varies spatially. As such, these localized resonance modes tend to be error-prone to the stochasticity of the target molecular orientations, vibrations and local concentrations^18,19. Here we identified enantioselective characteristics of collective resonances (CRs)²⁰ arising from assembled 2D crystals of isotropic, 432-symmetric chiral gold nanoparticles (helicoids)^21,22. The CRs exhibit a strong and uniform chiral near field over a large volume above the 2D crystal plane, resulting from the collectively spinning, optically induced dipoles at each helicoid. Thus, energy redistribution by molecular back action on the chiral near field shifts the CRs in opposite directions, depending on the handedness of the analyte, maximizing the modulation of the collective circular dichroism (CD).

DNA Origami Guided Self-Assembly of Plasmonic Polymers with Robust Long-Range Plasmonic Resonance

Plasmonic polymers consisting of metallic nanoparticles (NPs) are able to squeeze light into the deep-subwavelength space and transfer along a highly confined nanoscale path in long range. DNA nanotechnology, particularly benefiting from the molecular programmability of DNA origami, has provided otherwise nearly impossible platforms for constructing plasmonic nanoparticle polymers with designer configurations and nanoscale gaps. Here, we design and assemble a DNA origami hashtag tile that is able to polymerize into one-dimensional chains with high rigidity. The DNA origami hashtag chains are used as frames to enable robust, versatile, and precise arrangement of metallic NPs into micrometer-long chiral and magnetic plasmonic polymers, which are capable of efficiently transporting plasmonic angular momentum and magnetic surface plasmonic polaritons at the deep-subwavelength scale. Our work provides a molecular platform for the fabrication of long, straight, and structurally complex nanoparticle polymers with emerging plasmonic properties that are appealing to a variety of fields.

Exploiting Colloidal Metamaterials for Achieving Unnatural Optical Refractions

The scaling down of meta-atoms or metamolecules (collectively denoted as metaunits) is a long-lasting issue from the time when the concept of metamaterials was first suggested. According to the effective medium theory, which is the foundational concept of metamaterials, the structural sizes of meta-units should be much smaller than the working wavelengths (e.g., << 1/5 wavelength). At relatively low frequency regimes (e.g., microwave and terahertz), the conventional monolithic lithography can readily address the materialization of metamaterials. However, it is still challenging to fabricate optical metamaterials (metamaterials working at optical frequencies such as the visible and near-infrared regimes) through the lithographic approaches. This serves as the rationale for using colloidal self-assembly as a strategy for the realization of optical metamaterials. Colloidal self-assembly can address various critical issues associated with the materialization of optical metamaterials, such as achieving nanogaps over a large area, increasing true 3D structural complexities, and cost-effective processing, which all are difficult to attain through monolithic lithography. Nevertheless, colloidal self-assembly is still a toolset underutilized by optical engineers. Here, the design principle of the colloidally self-assembled optical metamaterials exhibiting unnatural refractions, the practical challenge of relevant experiments, and the future opportunities are critically reviewed.

Soft Plasmonic Assemblies Exhibiting Unnaturally High Refractive Index

The increases in refractive indices (n) of materials are crucial for transformative optical technologies. With the progress of monolithic lithography, large advances have been achieved with several semiconductors, including silicon, germanium, and gallium arsenide, which generally provide higher n of ∼4.0 compared to those of other elements. Nevertheless, above this upper limit of naturally available n, the range of light-matter interactions could be unprecedentedly expanded, which in turn enriches the possible applications. Here, we present a soft self-assembly of polyhedral Au colloids as a promising method to achieve unnaturally high n values. The interfacial assembly of Au nanocubes provides n of 6.4 at the resonant wavelength (near-infrared) and 4.5 in the off-resonant regimes (mid-infrared), which have not been previously reached. The soft self-assembly of polyhedral Au colloids can be a versatile and highly effective route for the fabrication of optical metamaterials with unnaturally high n values.

DNA Base Pair Stacking Crystallization of Gold Colloids

We describe a DNA base pair (bp) stacking driven 3D crystallization of 70-80 nm gold nanospheres (Au NSs) into a large-area, face-centered-cubic (FCC) lattice. Although great advances have been achieved over the past decade, DNA nanoparticle (NP) crystallization has relied solely on the base complementary binding. This limits the accessible crystal size particularly for the larger and heavier Au NPs (>50 nm). In this work, we argue that the use of DNA bp-stacking (so-called blunt-end stacking) instead of complementary binding can widen the scope of controlled interparticle interactions used to assemble larger Au colloids into a larger-area crystal. Through the optimization of the melting transition, relatively large Au NSs (e.g., 75 nm) with nearly ideal roundness can be crystallized into FCC crystals with the area of up to approximately 1400 μm². A strong metallodielectric stopband is experimentally observed in the visible range, confirming the high quality of our self-assembled Au colloidal crystals.

Bioinspired Toolkit Based on Intermolecular Encoder toward Evolutionary 4D Chiral Plasmonic Materials

Over the last two decades, nanophotonics, including plasmonics and metamaterials, have promised compelling opportunities for exotic control over light-matter interactions. The strong chiral light-matter interaction is a representative example. Three-dimensional (3D) chirality has existed naturally only in organic molecules and bio-organisms, but a negligible chiroptic effect was attained with these naturally occurring materials because of their small absorption cross sections. However, inspired by biological chirality, nanophotonic chiral materials have greatly expanded the design space of accessible chiroptic effects (e.g., pushing the chiral light-matter interaction to an exceptional regime, such as a broad-band circular polarizer, negative refractive index, and sensitive chiral sensing). Nevertheless, it is still a challenge to achieve precisely defined and dynamically reconfigurable chiral morphologies that further increase the chiroptic effect. Biological systems continue to inspire approaches to the design and synthesis of precisely defined 3D nanostructures. In particular, a living organism can program the evolutionary pathway of highly complexed 3D chiral morphology precisely from the molecular scale to the macroscopic scale while simultaneously enabling dynamic reconfiguration of their chirality. What if we could harness the power of biological selectivity and evolutionary capability in synthesizing chiral plasmonic materials? We envisioned that platform technology mimicking biological principles would enable control of 3D chiral structures for effective plasmonic interactions with polarized light and further impart the concept of time-dependent evolution (3D + 1D = 4D) to bring about responsive and dynamic changes in chiral plasmonics. In this Account, we review our efforts to develop the biomolecule-based synthesis of 3D chiral plasmonic materials and share the vision that as in biological systems, chirality can be programmed at the molecular level and hierarchically transferred at multiple scales to develop macroscopic chirality. Accompanied by a biomimetic time-dependent chirality of singular plasmonic nanometals, we also summarize recent achievements in the chemistry and nanophotonics communities pursuing 4D plasmonics that are closely related to our research. The biomimetic and bioinspired approaches discussed in this Account will provide new synthetic insights into implementing chiral nanomaterials and extend the range of accessible nanophotonic design. We hope that the molecular encoding approach will be useful to achieve dynamic light-matter interactions at unprecedented dimensions, time scales, and chirality.

Magnetic Plasmon Networks Programmed by Molecular Self-Assembly

Nanoscale manipulation of magnetic fields has been a long-term pursuit in plasmonics and metamaterials, as it can enable a range of appealing optical properties, such as high-sensitivity circular dichroism, directional scattering, and low-refractive-index materials. Inspired by the natural magnetism of aromatic molecules, the cyclic ring cluster of plasmonic nanoparticles (NPs) has been suggested as a promising architecture with induced unnatural magnetism, especially at visible frequencies. However, it remains challenging to assemble plasmonic NPs into complex networks exhibiting strong visible magnetism. Here, a DNA-origami-based strategy is introduced to realize molecular self-assembly of NPs forming complex magnetic architectures, exhibiting emergent properties including anti-ferromagnetism, purely magnetic-based Fano resonances, and magnetic surface plasmon polaritons. The basic building block, a gold NP (AuNP) ring consisting of six AuNP seeds, is arranged on a DNA origami frame with nanometer precision. The subsequent hierarchical assembly of the AuNP rings leads to the formation of higher-order networks of clusters and polymeric chains. Strong emergent plasmonic properties are induced by in situ growth of silver upon the AuNP seeds. This work may facilitate the development of a tunable and scalable DNA-based strategy for the assembly of optical magnetic circuitry, as well as plasmonic metamaterials with high fidelity.

Photofluidic Near-Field Mapping of Electric-Field Resonance in Plasmonic Metasurface Assembled with Gold Nanoparticles

We present a near-field mapping of electric fields from the individual superspherical and ultrasmooth gold nanoparticles (AuNPs) and artificially assembled AuNP nanostructures by measuring the reconfiguration of an azobenzene-containing polymer(azo-polymer) film. Various configurations of AuNPs and the azo-polymer were studied with atomic force microscopy measurements and calculations. The interference was systematically studied with AuNP dimers of various gap distances and different embedding depth in the polymer film. Finally, we successfully demonstrated the interference of standing waves in artificially assembled plasmonic metasurface.

iNKT cells prevent obesity-induced hepatic steatosis in mice in a C-C chemokine receptor 7-dependent manner

Non-alcoholic fatty liver disease and non-alcoholic steatohepatitis are characterized by an increase in hepatic triglyceride content with infiltration of immune cells, which can cause steatohepatitis and hepatic insulin resistance. C-C chemokine receptor 7 (CCR7) is primarily expressed in immune cells, and CCR7 deficiency leads to the development of multi-organ autoimmunity, chronic renal disease and autoimmune diabetes. Here, we investigated the effect of CCR7 on hepatic steatosis in a mouse model and its underlying mechanism. Our results demonstrated that body and liver weights were higher in the CCR7^−/− mice than in the wild-type (WT) mice when they were fed a high-fat diet. Further, glucose tolerance and insulin sensitivity were markedly diminished in CCR7^−/− mice. The number of invariant natural killer T (iNKT) cells was reduced in the livers of the CCR7^−/− mice. Moreover, liver inflammation was detected in obese CCR7^−/− mice, which was ameliorated by the adoptive transfer of hepatic mononuclear cells from WT mice, but not through the transfer of hepatic mononuclear cells from CD1d^−/− or interleukin-10-deficient (IL-10^−/−) mice. Overall, these results suggest that CCR7⁺ mononuclear cells in the liver could regulate obesity-induced hepatic steatosis via induction of IL-10-expressing iNKT cells.

Assembly of "3D" plasmonic clusters by "2D" AFM nanomanipulation of highly uniform and smooth gold nanospheres

Atomic force microscopy (AFM) nanomanipulation has been viewed as a deterministic method for the assembly of plasmonic metamolecules because it enables unprecedented engineering of clusters with exquisite control over particle number and geometry. Nevertheless, the dimensionality of plasmonic metamolecules via AFM nanomanipulation is limited to 2D, so as to restrict the design space of available artificial electromagnetisms. Here, we show that “2D” nanomanipulation of the AFM tip can be used to assemble “3D” plasmonic metamolecules in a versatile and deterministic way by dribbling highly spherical and smooth gold nanospheres (NSs) on a nanohole template rather than on a flat surface. Various 3D plasmonic clusters with controlled symmetry were successfully assembled with nanometer precision; the relevant 3D plasmonic modes (i.e., artificial magnetism and magnetic-based Fano resonance) were fully rationalized by both numerical calculation and dark-field spectroscopy. This templating strategy for advancing AFM nanomanipulation can be generalized to exploit the fundamental understanding of various electromagnetic 3D couplings and can serve as the basis for the design of metamolecules, metafluids, and metamaterials.

Using highly uniform and smooth selenium colloids as low-loss magnetodielectric building blocks of optical metafluids

We systematically analyzed the magnetodielectric resonances of Se colloids for the first time in an attempt to utilize them as building blocks for all-dielectric optical metafluids. By taking advantages of the synergistic properties of Se colloids, including their (i) high-refractive-index at optical frequencies, (ii) unprecedented structural uniformity, and (iii) ready availability, we were able to observe Kerker-type directional light scattering, resulting from the efficient coupling between strong electric and magnetic resonances, directly from Se colloidal suspensions. Thus, the use of Se colloids as a generic magnetodielectric building block suggests the opportunity for the production of fluidic low-loss optical antennas, which can be processed via spin-coating and painting.

Petal-Inspired Diffractive Grating on a Wavy Surface: Deterministic Fabrications and Applications to Colorizations and LED Devices

Interestingly, the petals of flowering plants display unique hierarchical structures, in which surface relief gratings (SRGs) are conformably coated on a curved surface with a large radius of curvature (hereafter referred to as wavy surface). However, systematic studies on the interplay between the diffractive modes and the wavy surface have not yet been reported, due to the absence of deterministic nanofabrication methods capable of generating combinatorially diverse SRGs on a wavy surface. Here, by taking advantage of the recently developed nanofabrication composed of evaporative assembly and photofluidic holography inscription, we were able to achieve (i) combinatorially diverse petal-inspired SRGs with controlled curvatures, periodicities, and dimensionalities, and (ii) systematic optical studies of the relevant diffraction modes. Furthermore, the unique diffraction modes of the petal-inspired SRGs were found to be useful for the enhancement of the outcoupling efficiency of an organic light emitting diode (OLED). Thus, our systematic analysis of the interplay between the diffractive modes and the petal-inspired SRGs provides a basis for making more informed decisions in the design of petal-inspired diffractive grating and its applications to optoelectronics.

Early-stage chronic kidney disease, insulin resistance, and osteoporosis as risk factors of sarcopenia in aged population: the fourth Korea National Health and Nutrition Examination Survey (KNHANES IV), 2008-2009

Sarcopenia means the progressive loss of skeletal muscle mass and strength with aging. In this study, we found that insulin resistance, chronic kidney disease stage 3, and osteoporosis at the femur neck were closely associated with sarcopenia in elderly men. These conditions modified to slow down the progression of sarcopenia.

INTRODUCTION

Sarcopenia is known to have multiple contributing factors; however, its modifiable risk factors have not yet been determined. The aim of this study was to identify the most influential and modifiable risk factors for sarcopenia in elderly.

METHODS

This was a population-based, cross-sectional study using data from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV), 2008-2009. This study included 940 men and 1,324 women aged 65 years and older who completed a body composition analysis using dual-energy X-ray absorptiometry. Sarcopenia was defined as an appendicular skeletal muscle mass divided by height(2) of less than 1 standard deviation below the sex-specific mean for a younger reference group.

RESULTS

Using univariate analysis, age, body mass index (BMI), homeostasis model assessment for insulin resistance (HOMA-IR), limitations in daily activities, regular exercise, high-risk drinking, family income, osteoporosis, daily energy, and protein intake were associated with sarcopenia in men; age, BMI, limitations in daily activities, regular exercise, occupation, osteoporosis at the total hip, and daily energy intake were associated with sarcopenia in women. In the multivariate logistic regression analysis, HOMA-IR ≥2.5 (odds ratio [OR] for sarcopenia, 2.27; 95 % confidence interval [CI], 1.21-4.25), chronic kidney disease stage 3 (OR, 3.13; 95 % CI, 1.14-8.61), and osteoporosis at the femur neck (OR, 6.83; 95 % CI, 1.08-43.41) were identified as risk factors for sarcopenia in men.

CONCLUSIONS

Insulin resistance, chronic kidney disease, and osteoporosis at the femur neck should be modified to prevent the acceleration of skeletal muscle loss in elderly men.

Gender-specific pleiotropic bone-muscle relationship in the elderly from a nationwide survey (KNHANES IV)

SUMMARY

The aim of this study was to examine the gender-specific association between sarcopenia and bone geometry/metabolic parameters. Low muscle mass was associated with greater deterioration of bone than in deterioration of glucose or lipid profiles. This bone-muscle relationship was more prominent in men than in women.

INTRODUCTION

There are few studies that report on gender differences in the effects of low muscle mass on bone and metabolic parameters in elderly subjects. This study aimed to assess the gender-specific influence of muscle mass on bone and metabolic parameters.

METHODS

A total of 2,264 participants (940 men and 1,324 women) whose age ranged from 65 to 92 years were analyzed using data from The Fourth Korea National Health and Nutrition Examination Surveys (2008-2009). We measured bone mineral density (BMD) and appendicular muscle mass using the dual-energy X-ray absorptiometry and also measured metabolic profiles.

RESULTS

The age-related trend in bone and muscle coincided in men but not in women. Femoral neck (FN) and total hip (TH) BMD were highly correlated with muscle mass in both genders. However, in women, this correlation was not significant in the lumbar spine (LS). In addition, this positive correlation was stronger in the FN or TH than in the LS and was stronger in men than in women. Subjects with sarcopenia were at a higher risk for osteoporosis in the FN, TH, and LS in men, and in the TH and FN in women. The degree of association between muscle mass and metabolic profiles was relatively very weak.

CONCLUSION

Bone-muscle relationship was more prominent in men than in women. The gender differences in bone-muscle relationship may be helpful for the development of gender-specific preventive strategies in the elderly, especially in men.

Dysregulation of miR-106a and miR-591 confers paclitaxel resistance to ovarian cancer

Background:

MicroRNAs are noncoding regulatory RNAs strongly implicated in carcinogenesis, cell survival, and chemosensitivity. Here, microRNAs associated with chemoresistance in ovarian carcinoma, the most lethal of gynaecological malignancies, were identified and their functional effects in chemoresistant ovarian cancer cells were assessed.

Methods:

MicroRNA expression in paclitaxel (PTX)-resistant SKpac sublines was compared with that of the PTX-sensitive, parental SKOV3 ovarian cancer cell line using microarray and qRT–PCR. The function of differentially expressed microRNAs in chemoresistant ovarian cancer was further evaluated by apoptosis, cell proliferation, and migration assays.

Results:

Upregulation of miR-106a and downregulation of miR-591 were associated with PTX resistance in ovarian cancer cells and human tumour samples. Transfection with anti-miR-106a or pre-miR-591 resensitized PTX-resistant SKpac cells to PTX by enhancing apoptosis (23 and 42% increase), and inhibited their cell migration (43 and 56% decrease) and proliferation (64 and 65% decrease). Furthermore, ZEB1 was identified as a novel target gene of miR-591, and BCL10 and caspase-7 were target genes of miR-106a, as identified by immunoblotting and luciferase assay.

Conclusion:

MiR-106a and miR-591 have important roles in conferring PTX resistance to ovarian cancer cells. Modulation of these microRNAs resensitizes PTX-resistant cancer cells by targeting BCL10, caspase-7, and ZEB1.

Early development of reflux esophagitis after successful Helicobacter pylori eradication in superficial gastritis

The relationship between gastroesophageal reflux disease (GERD) and Helicobacter pylori (H. pylori) eradication is still debated. Recently, we had a patient of GERD who had developed it shortly after H. pylori eradication therapy. A 72-year-old man was diagnosed by endoscopy as suffering from severe superficial gastritis in the stomach body. A rapid urease test showed H. pylori infection. He was then started on proton pump inhibitor (PPI) based therapy for two weeks eradicating H.pylori. After completion of H. pylori eradication, he complained of a heart-burn sensation. Follow-up endoscopy showed reflux esophagitis, of grade B according to the Los Angeles classification. Since the patient had developed GERD after completion of the triple therapy, their suggests that H. pylori eradication must have triggered the development of de novo GERD after a short period of time.

Down-regulation of claudin-2 in breast carcinomas is associated with advanced disease

AIMS

Claudin 2 (CLDN2) is a family of integral membrane tight junctions. The aim was to determine the influence of CLDN2 expression on tumour behaviour and its role in breast carcinogenesis.

METHOD AND RESULTS

Thirty-seven invasive breast carcinomas and corresponding normal breast tissues were examined for CLDN2 protein and mRNA expression using Western blotting and semiquantitative reverse transcriptase-polymerase chain reaction. The expression of CLDN2 protein in 118 cases of breast carcinoma was further studied with immunohistochemistry and related to various clinicopathological parameters. CLDN2 protein expression was significantly down-regulated (0.4-fold) in tumours compared with corresponding normal breast tissue (P < 0.0001). Down-regulation of CLDN2 was significantly associated with lymph node metastasis (P = 0.047) by Western blot analysis, and with high clinical stage (P = 0.040) by immunohistochemistry. The expression levels of CLDN2 mRNA in high clinical stages (stages II and III) were lower than those in low clinical stage (stage I) and normal tissue, but not statistically significantly so.

CONCLUSIONS

These results suggest that CLDN2 is implicated in the progression as well as the development of breast carcinoma, indicating that CLDN2 is a possible tumour suppressor gene product.

Yng2p-dependent NuA4 histone H4 acetylation activity is required for mitotic and meiotic progression

In all eukaryotes, multisubunit histone acetyltransferase (HAT) complexes acetylate the highly conserved lysine residues in the amino-terminal tails of core histones to regulate chromatin structure and gene expression. One such complex in yeast, NuA4, specifically acetylates nucleosome-associated histone H4. Recent studies have revealed that NuA4 comprises at least 11 subunits, including Yng2p, a yeast homolog of the candidate human tumor suppressor gene, ING1. Consistent with prior data, we find that cells lacking Yng2p are deficient for NuA4 activity and are temperature-sensitive. Furthermore, we show that the NuA4 complex is present in the absence of Yng2p, suggesting that Yng2p functions to maintain or activate NuA4 HAT activity. Sporulation of diploid yng2 mutant cells reveals a defect in meiotic progression, whereas synchronized yng2 mutant cells display a mitotic delay. Surprisingly, genome-wide expression analysis revealed little change from wild type. Nocodazole arrest and release relieves the mitotic defects, suggesting that Yng2p may have a critical function prior to or during metaphase. Rather than a uniform decrease in acetylated forms of histone H4, we find striking cell-to-cell heterogeneity in the loss of acetylated histone H4 in yng2 mutant cells. Treating yng2 mutants with the histone deacetylase inhibitor trichostatin A suppressed the mitotic delay and restored global histone H4 acetylation, arguing that reduced H4 acetylation may underlie the cell cycle delay.

Modifications of the Cox-Maze III procedure

BACKGROUND

The extended operative time needed for surgery with complicated atrial incisions may preclude application of the Cox-Maze III procedure (CM-III) as a concomitant operation. And after the CM-III, left atrial (LA) contraction has been reported to recover in reduced magnitude compared with right atrial (RA) contraction.

METHODS

To decrease operative time, we have modified the CM-III (modification I) by: obliterating the LA appendage instead of excising it; cryoablating the bridge between the LA appendage and margin of the pulmonary vein encircling incision; extending the lateral incision of RA onto the RA appendage without excising it, and extending the incision more inferiorly toward the inferior vena cava; and omitting the T-incision of RA. We compared the clinical results of the conventional CM-III (group 1, n = 18) with those of the modified CM-III group (group 2, n = 23) performed in patients with rheumatic mitral valve (MV) disease. To enlarge the contractile area of the LA, we modified the CM-III to encircle the right and left pulmonary veins separately (modification II), and compared the LA contractilities of the conventional CM-III (group A, n = 15) with those of the second modification (group B, n = 9).

RESULTS

Modification I: Mean aortic cross-clamp (ACC) times (135 +/- 29 versus 104 +/- 18 minutes, p < 0.005) and cardiopulmonary bypass (CPB) times (240 +/- 33 versus 185 +/- 42 minutes, p < 0.001) were significantly decreased in group 2 compared with those in group 1. In group 1, sinus rhythm was restored in 16 patients (88.9%). RA contractility was demonstrated in 100% of patients with sinus rhythm (16 of 16) and LA contractility in 75% (12 of 16) in the latest follow-up echocardiography. In group 2, sinus rhythm was restored in 21 patients (91.3%). RA contractility was demonstrated in 100% of patients with sinus rhythm (21 of 22) and LA contractility in 76.2% (16 of 21). Modification II: Mean ACC times were increased in group B compared with group A (133 +/- 32 versus 172 +/- 39 minutes, p = 0.02). The A velocities at LA contraction and the ratio of atrial contraction to peak early diastolic filling velocity (A/E ratio) of the trans-mitral flow were 0.14 +/- 0.20 m/sec and 0.23 +/- 0.11 in group A, and 0.58 +/- 0.33 m/sec and 0.47 +/- 0.19 in group B, respectively, both showing a significant increase in group B compared with group A (p < 0.05).

CONCLUSIONS

Our first modification of the CM-III showed comparable sinus conversion rates and incidence of atrial contractility restoration with significantly shorter ACC and CPB times than the conventional CM-III. The second modification of the CM-III significantly increased the LA contractility when compared with the conventional CM-III, although the second modification required a longer ACC time.

Time-dependent expression of ICAM-1 & VCAM-1 on coronaries of the heterotopically transplanted mouse heart

To investigate the pathogenesis of accelerated graft atherosclerosis after cardiac transplantation, a genetically well-defined and reproducible animal model is required. We performed heterotopic intraabdominal heart transplantation between the two inbred strains of mice. Forty hearts from B10.A mice were transplanted into B10.BR mice. Recipients were sacrificed at 1, 3, 5, 7, 14, 28, and 42 days after implantation. The specimens from both donor and recipient were examined with fluorescent immunohistochemistry and the serial histopathologic changes were evaluated. In the donor hearts, ICAM-1 and VCAM-1 expressions were minimal at day 1 and they gradually increased, reaching their peaks on day 5 or 7 and remained unchanged by day 42. However, there were very little expressions in the recipients' hearts. Mean percent areas of intima in the donor coronaries revealed progressive increase by day 42. However, those in the recipients occupied consistently less than 5% of the lumen. In conclusion, we demonstrated that a heterotopic murine heart transplantation model was a useful tool to produce transplantation coronary artery disease and that adhesion molecules on the cardiac allografts were activated very early and remained elevated at all time-points, nonetheless the arterial lesion was detected after day 28 and its progression was accelerated thereafter.