Manipulation of discrete nanostructures by selective modulation of noncovalent forces.

Covalent organic synthesis commonly uses the strategy of selective bond cleavage and formation. If a similar approach can be applied stepwisely to noncovalent synthesis, more exotic or challenging nanostructures might become achievable. Here, we report that ferrocene-based tetratopic pyridyl ligands, which can dynamically change their geometry by means of thermal rotation of their cyclopentadienyl rings in solution, assemble with AgBF4 into discrete metal-organic nanotubes with large and uniform diameters. The nanotubes can be cut into metal-organic nanorings through selective attenuation of the inter-nanoring interaction via ferrocene oxidation. The resultant nanorings can be transferred onto inorganic substrates electrostatically or allowed to reassemble to form the original nanotube by the reductive neutralization of their oxidized ferrocene units.

Discotic ionic liquid crystals of triphenylene as dispersants for orienting single-walled carbon nanotubes.

Orient and conduct: Triphenylene-based discotic ionic liquid crystals (ILCs) with six imidazolium ion pendants can disperse pristine single-walled carbon nanotubes (SWNTs). When the ILC is columnarly assembled, doping with SWNTs results in macroscopic homeotropic columnar orientation. Combination of shear and annealing treatments gives rise to three different orientation states, which determine the anisotropy of electrical conduction.

Autogenous osteochondral graft transplantation for steroid-induced osteonecrosis of the femoral condyle: A report of three young patients.

Steroid-induced osteonecrosis of the femoral condyle is a relatively uncommon condition and is often difficult to select appropriate treatment especially in young patients. Three young men (aged 25, 18, and 24) presented with severe pain and dysfunction of the knee diagnosed as steroid-induced osteonecrosis of the femoral condyle by magnetic resonance imaging (MRIs). Full-thickness cartilage defects sized 20 × 10, 15 × 10, and 30 × 20 mm respectively were classified as International Cartilage Repair Society Grade IV lesions and treated with osteochondral autograft transplantation. They were treated successfully with osteochondral autograft transplantation certificated by post-operative MRI and second look arthroscopy.

Autophagy modulates osteoarthritis-related gene expression in human chondrocytes.

OBJECTIVE: Autophagy, an evolutionarily conserved process for the bulk degradation of cytoplasmic components, serves as a cell survival mechanism. The purpose of this study was to elucidate the role of autophagy in human chondrocytes and pathophysiology of osteoarthritis (OA). METHODS: Autophagy in articular cartilage and primary chondrocytes was assessed using antibodies for the autophagy markers light chain 3 and beclin 1. The states of autophagy under catabolic and nutritional stresses were examined. We also examined the effects of inhibition or induction of autophagy under stimulation with interleukin-1ß. Autophagy was inhibited by small interfering RNA targeting ATG5, and autophagy was induced by rapamycin. The effects of inhibition or induction of autophagy were examined by real-time polymerase chain reaction for aggrecan, COL2A1, MMP13, and ADAMTS5 messenger RNA. To further examine the mechanism of autophagy regulation in OA human chondrocytes, we investigated whether autophagy modulates apoptosis and reactive oxygen species (ROS). RESULTS: Autophagy was increased in OA chondrocytes and cartilage. Catabolic and nutritional stresses increased autophagy. In addition, the inhibition of autophagy caused OA-like gene expression changes, while the induction of autophagy prevented them. Furthermore, the inhibition of autophagy increased the amount of cleaved poly(ADP-ribose) polymerase and cleaved caspase 9, while the induction of autophagy inhibited these increases. ROS activity was also decreased by induction of autophagy. CONCLUSION: These observations suggested that increased autophagy is an adaptive response to protect cells from stresses, and that autophagy regulates OA-like gene expression changes through the modulation of apoptosis and ROS. Further studies about autophagy in chondrocytes will provide novel insights into the pathophysiology of OA.

Comparison of the clinical outcome of double-bundle, anteromedial single-bundle, and posterolateral single-bundle anterior cruciate ligament reconstruction using hamstring tendon graft with minimum 2-year follow-up.

PURPOSE: The purpose of this study was to obtain more than 2 years' follow-up after surgery to investigate the effect of the difference in rotatory stability based on our previous data on the clinical outcome among 3 groups: double-bundle (DB) reconstruction group, anteromedial (AM) single-bundle reconstruction group, and posterolateral (PL) single-bundle reconstruction group. METHODS: We randomly separated 55 patients with anterior cruciate ligament rupture into 3 groups: 18 in DB group, 18 in AM group, and 19 in PL group. The mean follow-up period is 33.7 months for the DB group, 31.9 months for the AM group, and 33.2 months for the PL group. We evaluated the Lysholm score, Tegner score, anterior laxity with the KT-1000 arthrometer (MEDmetric, San Diego, CA), rotator instability with the pivot-shift test, and muscle strength with knee extensor and flexor isokinetic peak torques at 60°/s. RESULTS: There were no significant differences in postoperative Lysholm score and Tegner score. Anterior stability of the knee, as measured by the KT-1000 arthrometer, was significantly better in the DB group than the PL group (P < .05). The negative rate of the manual pivot-shift test in the DB group was significantly superior to the PL group (P < .05). Muscle strength of the extensor in the DB group was significantly superior to that in the AM group (P < .05), and muscle strength of the flexor in the PL group was significantly inferior to that in both the DB and AM groups (P < .05). Two patients in the PL group had rerupture; however, there was no graft failure in the other groups. CONCLUSIONS: At 2 years' follow-up, patients undergoing DB anterior cruciate ligament reconstruction had greater extension strength than patients receiving an AM single-bundle reconstruction. The DB and AM groups had greater flexion strength than the PL group. The DB and AM groups had a similar rate of negative pivot-shift test results, whereas the PL group had fewer negative pivot-shift test results than the DB group. There were no KT-1000 side-to-side differences between the DB and AM groups, whereas the DB group had better results than the PL group. Overall, the clinical outcome as measured by Lysholm and Tegner scores was not different between groups. LEVEL OF EVIDENCE: Level II, prospective comparative study.

Potential involvement of SIRT1 in the pathogenesis of osteoarthritis through the modulation of chondrocyte gene expressions.

SIRT1 has been implicated as a key factor in aging-related diseases. Nevertheless, the role of SIRT1 in the pathogenesis of osteoarthritis (OA) is still unknown. We examined the expression of SIRT1 in cartilage samples and the effect of SIRT1 inhibition on chondrocyte gene expression changes to elucidate the role of SIRT1 in chondrocytes. SIRT1 expression was examined using cartilage samples from patients undergoing total knee arthroplasty and femoral head replacement by immunohistochemistry. The effect of SIRT1 inhibition by siRNA on chondrocyte gene expression was examined by real-time PCR and Western blotting. SIRT1 expression was barely detectable in the severely degenerated cartilage while SIRT1 was clearly expressed in the less damaged cartilage. The inhibition of SIRT1 by siRNA induced OA-like gene expression changes, namely the significant down-regulation of aggrecan and up-regulation of COL10A1 and ADAMTS-5. Our observations suggest that SIRT1 expression decreases with development of OA and the reduction of SIRT1 in chondrocytes may cause chondrocyte hypertrophy and cartilage matrix loss. SIRT1 might play important roles in the pathogenesis of OA.

Spontaneous formation of dye-functionalized gold nanoparticles using reverse micellar systems.

Detailed exploratory and mechanistic investigations on spontaneous formation of dye-functionalized gold nanoparticles (GNPs) using dye-based reverse micellar systems are described in this publication. The accumulated results from spectroscopic and microscopic investigations demonstrated that water molecules confined within nanoscopic enclosure of the self-assembled reverse micelles played critical role in the redox processes of aurate ions to produce GNPs, which are assumed to have approximately constant size distributions. The resulting dye-functionalized GNPs were found to offer their absorption and fluorescence emission tunability by changing the medium polarity as well as to exhibit excellent film-forming properties to give optically homogeneous polystyrene thin films. These key findings in addition to broad applicability of the self-assembling process with a variety of dye analogues have led to a conclusion that the protocol presented here serves as a versatile synthetic method to provide a potential convenience for future development of new organic-inorganic hybrid nanomaterials.

A prospective randomised study of anatomical single-bundle versus double-bundle anterior cruciate ligament reconstruction: quantitative evaluation using an electromagnetic measurement system.

We conducted a prospective randomised study of anatomical single-bundle (A-SB group) versus double-bundle (A-DB group) anterior cruciate ligament (ACL) reconstruction using the hamstrings tendons. Twenty patients with unilateral ACL deficiency were randomised into two groups. We created the bone tunnels at the position of the original insertion of the anteromedial bundle footprint and posterolateral bundle footprint in the A-DB group and at the central position between these two bundles in the A-SB group. All of the patients were tested before ACL reconstruction and one year after surgery. The KT-1000 measurements, isokinetic muscle peak torque and heel-height difference were evaluated and the general knee condition was assessed by Lysholm score. For pre- and postoperative stability assessment, we used the six-degrees-of-freedom of knee kinematic measurement system using an electromagnetic device (the EMS) for quantitative assessment during the Lachman test and the pivot shift test. There were no significant differences in the KT-1000 measurements, isokinetic muscle peak torque, heel-height difference, and Lysholm score at one-year follow-up between these two groups. The EMS data showed there were significant differences in the acceleration of the pivot shift test between the operated knee and the contralateral normal knees in the A-SB group. In conclusion, clinical outcomes were equally good in both groups. However, the EMS data showed the anatomical double-bundle ACL reconstruction tended to be biomechanically superior to the single-bundle reconstruction.

Coupling of a C2-chiral ferrocene with phenylalkynyl groups: novel ferrocenophanes carrying multiple chiral ferrocenyl units.

Upon treatment with CuCl/TMEDA (1:1) at a high [CuCl]/[1] ratio, enantiopure C(2)-chiral tetrasubstituted ferrocene 1 carrying phenylalkynyl groups is transformed into a novel family of chiral ferrocenophanes 2 and 3 with their ferrocenyl joints connected by a pi-conjugated rigid bridge. Compound 3, which is reminiscent of the Escher's endless staircase, is a single conformer with a one-handed helical chirality.

Studies on a new class of organogelator containing 2-anthracenecarboxylic acid: influence of gelator and solvent on stereochemistry of the photodimers.

A new class of binary organogelator (G1, G2 and G3) based on 2-anthracenecarboxylic acid (2Ac), attached noncovalently with the gelator counterpart containing a 3,4,5-tris(n-dodecyloxy)benzoylamide backbone has been developed. Among the three gelators, two (G2 and G3) are chiral containing D-alanine or L-2-phenylglycine moieties, respectively. They can act as efficient gelators of organic solvents with varying polarity depending upon the gelator systems. Gelator G1 even gelates chiral solvents. The photoirradiation of the gel samples produces photocyclodimers having different degrees of stereoselectivity for different systems. Gels with G1 and G2 produce head-to-head (h-h) photodimers as major products, whereas the stereoselectivity is reversed for the gels with G3 producing head-to-tail (h-t) photodimers as major products. Among those, G2/cyclohexane gel shows the highest degree of stereoselectivity, producing only h-h photodimers with some significant amount of chiral induction. Other chiral systems exhibit low to moderate chiral inductions. The gelator G1 can differentiate between the racemic and enantiomerically pure varieties of a solvent by exhibiting different gel melting temperatures (T(gel)). For different gel systems, T(gel) increases in all the cases as a consequence of photoreaction, except for the G2/cyclohexane gel, where a prominent gel-to-sol phase transition can be observed during the photoreaction. Hydrogen-bonding and pi-pi stacking interactions play the principal roles in constructing the gel structure. The morphologies of the gel systems vary between one-dimensional fibrils and a fibrillar network structure. In addition, the influences of the gelator and solvent polarity on the rate of photoreactions, photoproduct distributions as well as gel structures are investigated.

SIRT1 regulation of apoptosis of human chondrocytes.

OBJECTIVE: SIRT1 is known to inhibit apoptosis and to promote survival of various types of cells. However, the roles of SIRT1 in apoptosis of human chondrocytes have never been reported. We undertook this study to investigate the relationship of SIRT1 to apoptosis of human chondrocytes, which is a characteristic feature of osteoarthritis (OA). METHODS: The expression of SIRT1 in human chondrocytes was examined by reverse transcription-polymerase chain reaction, immunoblotting, and immunohistology of human cartilage samples. The expression of SIRT1 under catabolic, mechanical, and nutritional stresses was investigated by immunoblotting. To examine the effect of SIRT1 on apoptosis, SIRT1 was inhibited by small interfering RNA (siRNA) and activated by resveratrol during nitric oxide (NO)-induced apoptosis. TUNEL staining and immunoblotting of cleaved poly(ADP-ribose) polymerase (PARP) were performed to detect apoptosis. To examine the mechanisms of apoptosis, we used immunoblotting to determine the levels of cleaved caspases and mitochondria-related apoptotic signaling proteins, Bax and Bcl-2, in the mitochondrial fraction. RESULTS: SIRT1 expression was confirmed in human chondrocytes and human cartilage samples. All catabolic, mechanical, and nutritional stresses inhibited SIRT1 expression. SIRT1 inhibition by siRNA for SIRT1 increased the percentage of TUNEL-positive cells and increased the amounts of cleaved PARP and cleaved caspases 3 and 9 induced by NO. In contrast, treatment with resveratrol decreased the percentage of TUNEL-positive cells and decreased the amounts of cleaved PARP and cleaved caspases 3 and 9 induced by NO. Furthermore, in the mitochondrial fraction, SIRT1 inhibition by siRNA for SIRT1 increased the amount of Bax but reduced the amount of Bcl-2, while resveratrol reduced the amount of Bax but increased the amount of Bcl-2. CONCLUSION: These results indicate that SIRT1 regulates apoptosis in human chondrocytes through the modulation of mitochondria-related apoptotic signals. Further research on SIRT1 might contribute to resolving the pathogenesis of OA.

Bilateral double-layered lateral meniscus: a report of two cases.

Only a few cases of double-layered meniscus have been described in the English literature. We report two cases of bilateral double-layered lateral meniscus, where an additional semicircular meniscus was observed over the normal lateral meniscus. One of the patients exhibited a bucket-handle tear with a double-layered meniscus. To our knowledge, this abnormality is extremely rare and the incidence of double layered meniscus with bucket-handle tear has not been previously reported.

An organogel system can control the stereochemical course of anthracene photodimerization.

A novel photoresponsive organogel with a binary gelator containing 2-anthracenecarboxylic acid shows a high degree of stereochemical control, resulting in head-to-head photocyclodimers exclusively together with significant enantiomeric excess induced by the chiral counterpart of the gelator.

Crystal engineering approach to design colorimetric indicator array to discriminate positional isomers of aromatic organic molecules.

Discriminating by color: A 2D colorimetric indicator array has been designed by a crystal engineering approach (NH-O hydrogen bonding and charge-transfer complexation) involving solid-state co-grinding for the visual discrimination of positional isomers of dihydroxynaphthalene. Factors governing the close packing of pi planes, and hence color of the complex, were determined by single-crystal X-ray analysis, allowing fine tuning by crystal engineering. A 2D colorimetric indicator array to discriminate isomers of dihydroxynaphthalene has been designed by using a crystal engineering concept combined with solid-state co-grinding and charge-transfer complexation. The NH-O supramolecular synthon between the pyridyl N atom of the probe and hydroxy group of the analyte has been observed in all reported single-crystal X-ray structures of resultant CT complexes. Solid-state co-grinding with aromatic solids easily provided the highly concentrated solvent-free conditions required to promote the formation of charge-transfer complexes with brighter color changes. Probe D (N,N'-bis-(4-pyridyl)pyromellitic diimide) showed an excellent ability to discriminate eight isomers of dihydroxynaphthalene with a wide variety of colors of the resultant CT complexes.

Boronic acids in molecular self-assembly.

The reversibility of boronic acid and diol interaction makes it an ideal candidate for the design of self-assembled molecular structures. Reversibility is required to ensure that the thermodynamically most stable structure is formed. Reversibility also ensures that any errors produced during the assembly process are not permanent.

Angle-controlled arrangement of single-walled carbon nanotubes solubilised by 8-quinolinol metal chelate derivatives on mica.

We solubilised SWNTs of short length using a mechanochemical high-speed vibration milling (HSVM) through formation of complexes between the SWNTs and chelate complexes; the mixture formed a network structure on mica.

Creation of polynucleotide-assisted molecular assemblies in organic solvents: general strategy toward the creation of artificial DNA-like nanoarchitectures.

The influence of added polynucleotide on the gelation ability of nucleobase-appended organogelators was investigated. Uracil-appended cholesterol gelator formed a stable organogel in polar organic solvents such as n-butanol. It was found that the addition of the complementary polyadenylic acid (poly(A)) not only stabilizes the gel but also creates the helical structure in the original gel phase. Thymidine and thymine-appended gelators can form stable gel in apolar solvents, such as benzene, where poly(A)-lipid complex can act as a complementary template for the gelator molecules to create the fibrous composites. Based on these findings, we can conclude that self-assembling modes and gelation properties of nucleobase-appended organogelators are controllable by the addition of their complementary polynucleotide in organic solvents. We believe, therefore, that the present system can open the new paths to accelerate development of well-controlled one-dimensional molecular assembly systems, which would be indispensable for the creation of novel nanomaterials based on organic compounds.