Effects of Operating Mechanical Conditions and Polymer Networks of Nematic Elastomers on Photo-Induced Mechanical Performances

Photoresponsive liquid-crystalline elastomers (LCEs) are promising candidates for light-controlled soft actuators. Photoinduced stress/strain originates from the changes in mechanical properties after light irradiation. However, the correlation between the photoinduced mechanical performance and in-use conditions such as stress/strain states and polymer network properties (such as effective crosslink density and dangling chain density) remains unexplored for practical applications. Here, isometric photo-induced stress or isotonic strain is investigated at different operating strains or stresses, respectively, on LCEs with polymer network variations, produced by different amounts of solvent during polymerization. As the solvent volume increases, the moduli and photoinduced stresses decrease. However, the photo-induced strain, fracture strain, fracture stress, and viscosity increase. The optical response performance initially increases with the operating strain/stress, peaks at a higher actuation strain/stress, and then, decreases depending on the polymer network. The maximum work densities, which also depend on the operating stress, are in the range of ≈200-300 kJm-3. These findings, highlighting the significant variations in the mechanical performance with the operating stress/strain ranges and amount of solvent used in the synthesis, are critical for designing LCE-based mechanical devices.

COMT Val/Met, stressful life events and externalizing behaviors in youth: A longitudinal study from the ABCD sample

Early adolescence is a crucial time for understanding and detecting the risk factors that may influence youth externalizing/disruptive behaviors and disorders. Previous literature reported evidence that risk factors for disruptive behaviors include catechol-O-methyltransferase (COMT) Val158Met (rs4680) polymorphism and environmental influences. An unanswered question is whether there is a change in these risk factors over stages of youth development. This longitudinal study examines the interaction effect of Val158Met and stressful life events (SLE) on youth externalizing behaviors from ages 9-11. Participants were 2363 children of European ancestry recruited as part of the Adolescent Brain Cognitive Development study. Repeated measures linear mixed models were used to examine the effect of the interaction between Val158Met and SLE (G × E) on disruptive behaviors over development. Externalizing behaviors were analyzed at both baseline and two-year follow-up. Both Val158Met genotype and SLE scores demonstrated significant main effects on disruptive behaviors in youth, and those effects were consistent at both time points. G × E was not associated with externalizing behaviors. Youth who carried the Val allele and/or were exposed to higher SLE consistently had increased externalizing behavior scores. To our knowledge, this is the first study to longitudinally examine the interaction effects of Val158Met and SLE on externalizing behaviors in youth. The results highlight the importance of understanding the genetic and environmental factors underlying externalizing behaviors for better detection of at-risk youth, helping further with early prevention efforts. The findings propose that COMT Val158Met genotype may act as a biomarker for development of novel treatment strategies for disruptive behaviors.

Association of the MAOA-uVNTR polymorphism with psychopathic traits may change from childhood to adolescence

Psychopathic traits can lead to violence, making it a serious public health concern. Genetic factors contribute to the aetiology of psychopathy. We examined whether monoamine oxidase A (MAOA-uVNTR) was associated with psychopathic traits measured quantitatively from controls through clinically aggressive youth (n = 336). Subjects were sub-categorized into at or above, and below age 13 years. Results reveal that males below age 13 were more likely to display psychopathic traits with the MAOA long variant, whereas males above age 13 years were more likely to display with the short variant. This suggests that developmental factors may be crucial for understanding the role of the MAOA polymorphism in psychopathic traits in males.

Exploring the association of interleukin polymorphisms with aggression and internalizing behaviors in children and adolescents

BACKGROUND

There is growing evidence that inflammation influences mental health. Blood interleukin levels, which regulate inflammation, have been linked to aggression and internalizing behaviors. We performed a hypothesis-driven genetic study to (1) evaluate the association of IL1B, IL2, and IL6 gene variants with aggression and internalizing behaviors and (2) explore gene-environment interactions with childhood adversity in a deeply phenotyped childhood-onset aggression sample including 255 cases and 226 controls of European ancestry.

METHODS

We evaluated the association of putative functional and tag SNPs within IL1B, IL2, and IL6 with aggression case status, parent-reported internalizing problems, self-reported anxiety symptoms, and self-reported depressive symptoms in our sample. We also performed exploratory GxE analyses within cases, testing for statistical interaction between interleukin SNP genotype and childhood adversity for depressive symptoms.

RESULTS

No significant association was observed between any of the interleukin SNPs and childhood-onset aggression. We observed association of IL6 variant rs2069827 with depressive symptoms (p = 7.15×10^-4 ), and trends for an interaction between severe childhood adversity and SNPs in IL1B and IL2 for depressive symptoms.

CONCLUSIONS

Our findings provide preliminary evidence that common variation in IL6 may be associated with depressive symptoms in children and adolescents, and that common variation in interleukin genes may sensitize individuals to the depressogenic effects of traumatic life experiences. Replication in independent samples is needed.

Photo-Rewritable Glaring Patterns Composed of Stripe Domains in Nematic Elastomers

Dynamic ordered micropatterns in polymeric materials provide an effective approach for the on-demand tuning of optical properties toward a smart optical material. In this study, we show that glaring patterns exhibiting strong anisotropic light diffusion can be developed at specific locations in nematic liquid-crystal elastomers with light-sensitive azobenzene units. Glaring originates from the stripe domains of the nematic directors that self-organize in light-irradiated regions after a simple uniaxial stretching and releasing process without any complicated lithographic technique. The nematic order transiently reduced by the photo-induced cis azobenzene isomers unlocks entropic elasticity, which induces local uniaxial shrinkage that causes buckling of the directors forming stripe domains. The written pattern on the film is tangibly visible with the backlight owing to the difference in anisotropic light diffusion. Furthermore, this pattern can be erased by light irradiation or thermal annealing. These films can be applied to optical elements for achieving augmented luminaries, security labeling, and sign-sheeting applications. This article is protected by copyright. All rights reserved.

Effects of photo-isomerizable side groups on the phase and mechanical properties of main-chain nematic elastomers

A series of main-chain nematic liquid crystal elastomers containing various photo-isomerizable side groups branching from the main chain were synthesized. The effects of the side groups on the thermal phase and mechanical properties were explored.

Halogen bond-directed self-assembly in bicomponent blends at the solid/liquid interface: Effect of the alkyl chain substitution position

The fabrication of well-organised molecular assemblies on surfaces is fundamental for the creation of functional molecular systems applicable to nanoelectronics and molecular devices. In this study, we investigated the effect...

Pharmacogenomic Studies in Intellectual Disabilities and Autism Spectrum Disorder: A Systematic Review

BACKGROUND

Individuals with intellectual disability (ID) and autism spectrum disorder (ASD) often receive psychotropic medications such as antipsychotics and antidepressants to treat aberrant behaviors and mood symptoms, frequently resulting in polypharmacy and drug-related adverse effects. Pharmacogenomic (PGx) studies with ASD and/or ID (ASD/ID) have been scarce despite the promise of optimizing treatment outcomes. We reviewed the literature on PGx studies with antipsychotics and antidepressants (e.g., treatment response and adverse effects) in ASD/ID.

METHODS

We performed a systematic review using MEDLINE, Embase, and PsycINFO, including peer-reviewed original articles in English referring to PGx in the treatment of ASD/ID in any age groups (e.g., treatment response and adverse effects).

RESULTS

A total of 28 PGx studies using mostly candidate gene approaches were identified across age groups. Notably, only 3 studies included adults with ASD/ID while the other 25 studies focused specifically on children/adolescents with ASD/ID. Twelve studies primarily investigated treatment response, of which 5 and 6 studies included patients treated with antipsychotics and antidepressants, respectively. Most interesting results for response were reported for 2 sets of candidate gene studies, namely: (1) The DRD3 Ser9Gly (rs6280) polymorphism was examined in patients treated with risperidone in 3 studies, 2 of which reported an association with risperidone treatment response and (2) the SLC6A4 5-HTTLPR polymorphism and treatment response to antidepressants which was investigated in 4 studies, 3 of which reported significant associations. In regard to side effects, 9 of 15 studies focused on hyperprolactinemia in patients treated with risperidone. Among them, 7 and 5 studies examined the impact of CYP2D6 and DRD2 Taq1A polymorphisms, respectively, yielding mostly negative study findings.

CONCLUSIONS

There is limited data available on PGx in individuals with ASD/ID and in particular in adults. Given the potential for PGx testing in improving treatment outcomes, additional PGx studies for psychotropic treatment in ASD/ID across age groups are warranted.

Genome-wide association study of suicidal behaviour severity in mood disorders

OBJECTIVE

Suicide is a major public health problem and it has a prominent genetic component. We performed a genome-wide association study (GWAS) of suicidal behaviour severity.

METHODS

Suicide behaviour severity was assessed within the Schedules for Clinical Assessment in Neuropsychiatry in our mood disorder sample (n = 3506) for the GWAS. We also performed polygenic risk score analyses to explore genetic sharing between suicidal behaviour severity and a number of phenotypes, including bipolar disorder, major depressive disorder, alcoholism, post-traumatic stress disorder, impulsivity, insomnia, educational attainment, loneliness, maltreatment, and amygdala volume.

RESULTS

We did not detect genome-wide significant findings at the single-marker or gene level. We report a number of suggestive single-marker and gene-based findings. Our polygenic risk score analyses did not yield significant findings with these phenotypes.

CONCLUSIONS

Larger sample sizes are required to detect moderate effects.

Cephalopods-Inspired Rapid Self-Healing Nanoclay Composite Coatings with Oxygen Barrier and Super-Bubble-Phobic Properties

Polymeric coatings with oxygen barrier properties are an important technology in food packaging that can extend the shelf life of food products and reduce waste. Although a typical technology in practical use is the deposition of metal or inorganic materials between multilayer films to reduce the oxygen transmission rate, once the film is damaged, oxygen permeates through the damaged area, damaging the packaged food. In addition, nanobrick wall structures consisting of nanoplatelet bricks have the potential to replace barrier films made of inorganic materials; however, they similarly lack repair performance or have slow repair speed despite having repair performance. Inspired by the rapid self-repair mechanism of cephalopods, the study develops a nanoclay-containing coating that can rapidly repair surface damage via water within 10 s. By introducing CaCl₂-derived counterions and montmorillonite for nanobrick wall structures into polyelectrolyte multilayers stacked by layer-by-layer self-assembly, the noncovalent polymer network is increased, resulting in mimicking a strong cephalopod-derived β-sheet structure and noncovalent intermolecular interactions derived from cephalopods. The high water retention at the surface showed super-bubble-phobicity in water and inhibited gas permeation. The oxygen permeability of the coatings with more than a certain amount of montmorillonite was less than 1/100 of that of bare polyethylene. The ultrafast self-healing gas barrier coating has the potential to be used not only for food products but also for electronics and pharmaceutical packaging and gas separation applications. The key technology developed in this study provides novel insights into the construction of self-healing membranes made of composite materials and will contribute to the formation of a sustainable society.

Evidence for association of vasopressin receptor 1A promoter region repeat with childhood onset aggression

OBJECTIVE

Childhood onset aggression can cause major suffering to affected families and is associated with many negative outcomes in the child's later life, including poor academic performance, adolescent delinquency, drug abuse, depression and antisocial personality disorder. Currently available prevention and intervention strategies have limited efficacy, but a better understanding of underlying genetic and neurobiological factors can lead to more effective prevention and treatment strategies, through genetic screening programs and novel therapies.

METHOD

This study examined the RS1 (n = 299 aggression, n = 192 controls) and RS3 (n = 291 aggression, n = 189 controls) microsatellite repeats within the promoter region of the vasopressin receptor 1A gene (AVPR1A) and their association with extreme childhood aggression, as assessed by the Child Behavior Checklist (CBCL), as well as the Teacher Report Form (TRF) and Youth Self Report (YSR). Binary logistic regression was used to model the relationship between microsatellite length and childhood aggression. Age and sex were used as covariates.

RESULTS

Logistic regression revealed a nominally significant association between one specific RS3 repeat and non-aggressive status. No association was found for any of the RS1 repeats. In a separate model, grouping repeats into short and long, carriers of long RS3 repeats were nominally significantly associated with non-aggressive status.

CONCLUSIONS

These findings suggest a role for AVPR1A and its RS3 microsatellite in extreme childhood aggression and could lead to a better understanding of the biological pathways of aggressive behavior. However, independent replication and further research into the functionality of studied genetic variants is required.

Dynamic host-guest behavior in halogen-bonded two-dimensional molecular networks investigated by scanning tunneling microscopy at the solid/liquid interface

The fabrication of supramolecularly engineered two-dimensional (2D) networks using simple molecular building blocks is an effective means for studying host-guest chemistry at surfaces toward the potential application of such systems in nanoelectronics and molecular devices. In this study, halogen-bonded molecular networks were constructed by the combination of linear halogen-bond donor and acceptor ligands, and their 2D structures at the highly oriented pyrolytic graphite/1-phenyloctane interface were studied by scanning tunneling microscopy. The bi-component blend of the molecular building blocks possessing tetradecyloxy chains formed a lozenge structure via halogen bonding. Upon the introduction of an appropriate guest molecule (e.g., coronene) into the system, the 2D structure transformed into a hexagonal array, and the central pore of this array was occupied by the guest molecules. Remarkably, the halogen bonding of the original structure was maintained after the introduction of the guest molecule. Thus, the halogen-bonded molecular networks are applicable for assembling guest species on the substrate without the requirement of the conventional rigid molecular building blocks with C 3 symmetry.

Predicting risk of suicidal ideation in youth using a multigene panel for impulsive aggression

Childhood traumatic experiences and impulsive aggression are strong predictors of suicide ideation in youth.  This study examines whether a gene panel previously associated with impulsive aggression, together with a measure of traumatic experience, will predict suicidal ideation in youth. The sample consisted of 158 youth (ages 9-17 years) of European ancestry that participated in a case-control study for childhood aggression.  The Massachusetts Youth Screening Instrument (MAYSI-2) was used to examine suicide ideation and traumatic experiences. The impulsive aggression gene panel consists of 5 markers across 5 susceptibility genes (CRH, CRHR2, MC2R, OXTR, BDNF). A multi-gene risk score (MRS) for each individual was calculated by taking the total number of risk genotypes for that person. The covariates for the multiple regression model included sex, age, symptoms of anxiety/depression, MRS, traumatic experiences, and MRS x traumatic experience interaction. Results show the MRS x traumatic experience interaction term and the anxious/depressed symptoms to be significant predictors of suicide ideation in the full model. Importantly, genetic susceptibility to impulsive aggression and traumatic experiences remained a significant predictor for suicide ideation over and above the youth's level of anxiety and depression. This finding may have important implications for early intervention for youth suicide-related behaviors.

Hexagonal array formation by intermolecular halogen bonding using a binary blend of linear building blocks: STM study

Hexagonal arrays were fabricated via intermolecular halogen bonding between two linear molecular building blocks in a bicomponent blend. The substitution position of the pyridine N atom involved in the halogen bond plays an important role in the formation of the hexagonal structures.

Light-induced mechanical response in crosslinked liquid-crystalline polymers with photoswitchable glass transition temperatures

Energy conversion of light into mechanical work is of fundamental interest in applications. In particular, diligent molecular design on nanoscale, in order to achieve efficient photomechanical effects on macroscopic scale, has become one of the most interesting study topics. Here, by incorporating a "photomelting" azobenzene monomer crosslinked into liquid crystalline (LC) networks, we generate photoresponsive polymer films that exhibit reversible photoswitchable glass transition temperatures (Tg) at room temperature (~20 °C) and photomechanical actuations under the stimulus of UV/visible light. The trans-to-cis isomerization of azo chromophores results in a change in Tg of the crosslinked LC polymers. The Tg of the polymer network is higher than room temperature in the trans-form and lower than room temperature in the cis-form. We demonstrate the photoswitchable Tg contribute to the photomechanical bending and a new mechanism for photomechanical bending that attributes the process to an inhomogeneous change in Tg of the film is proposed.

Cannabis use, other substance use, and co-occurring mental health concerns among youth presenting for substance use treatment services: Sex and age differences

Cannabis use among youth is of significant concern given the potential negative health impacts on young people. This study describes the mental health characteristics, cannabis use, and substance use profiles of youth aged 14 to 24 years seen at the Youth Addiction and Concurrent Disorders Service at the Centre for Addiction and Mental Health, through an age and gender lens. Almost all participating youth indicated lifetime cannabis use. Substance use and mental health profiles among those indicating a history of cannabis use differed along sex and age. Male youth were more likely to use cannabis more frequently, while female youth were more likely to use greater variety of substances and display more co-occurring mental health problems. Adolescent problematic substance use tended to co-occur with externalizing problems whereas problematic young adult substance use tended to co-occur with internalizing problems. Implications for the integrated, coordinated care of substance use and mental health concerns, with attention to the unique needs of subgroups of youth, are discussed.

Circadian Rhythm Estimation by Core Body Temperature Filtered with Simultaneously Recorded Physiological Data

In field measurements, monitoring of core body temperature is influenced by physical activities; therefore, the estimation of circadian rhythm from the data may not be exact. The purpose of this study is to design a core body temperature filter in order to reduce artifacts induced by physical activities using simultaneously recorded physiological data such as heart rate data.

The effects of physical activities on core body temperature and heart rate are assessed through three experiments. Based on the above knowledge, a core body temperature filter was designed. The filter removes part of rectal temperature data as artifact when heart rate rises above a predetermined threshold. As a result, most of the spike-like noise was removed and the filtered temperature data showed sinusoidal variation more than the unfiltered data. The mesor of the estimated rhythm significantly decreased. This filtering method can provide more precise information about circadian rhythm, especially in field measurements.

The Versican G1 Fragment and Serum-Derived Hyaluronan-Associated Proteins Interact and Form a Complex in Granulation Tissue of Pressure Ulcers

The hyaluronan (HA)-rich extracellular matrix plays dynamic roles during tissue remodeling. Versican and serum-derived HA-associated protein (SHAP), corresponding to the heavy chains of inter-α-trypsin inhibitor, are major HA-binding molecules in remodeling processes, such as wound healing. Versican G1-domain fragment (VG1F) is generated by proteolysis and is present in either remodeling tissues or the mature dermis. However, the macrocomplex formation of VG1F has not been clarified. Therefore, we examined the VG1F-containing macrocomplex in pressure ulcers characterized by chronic refractory wounds. VG1F colocalized with SHAP-HA in specific regions of the granulation tissue but not with fibrillin-1. A unique VG1F-SHAP-HA complex was isolated from granulation tissues using gel filtration chromatography and subsequent cesium chloride-gradient ultracentrifugation under dissociating conditions. Consistent with this molecular composition, recombinant versican G1, but not versican G3, interacted with the two heavy chains of inter-α-trypsin inhibitor. The addition of recombinant VG1 in fibroblast cultures enhanced VG1F-SHAP-HA complex deposition in the pericellular extracellular matrix. Comparison with other VG1F-containing macrocomplexes, including dermal VG1F aggregates, versican-bound microfibrils, and intact versican, highlighted the tissue-specific organization of HA-rich extracellular matrix formation containing versican and SHAP. The VG1F-SHAP-HA complex was specifically detected in the edematous granulation tissues of human pressure ulcers and in inflamed stages in a mouse model of moist would healing, suggesting that the complex provides an HA-rich matrix suitable for inflammatory reactions.

Language disorder and retrospectively reported sexual abuse of girls: severity and disclosure

BACKGROUND

Despite emerging evidence for an association between communication disorders and maltreatment, little research has examined sexual abuse characteristics or disclosure experiences among individuals with language disorder (LD). Given that communication difficulties may constitute a barrier to disclosure, the disclosure experiences among individuals with and without communication difficulties may also differ.

METHODS

Five-year-old children identified with a language and/or speech disorder from a nonclinical community sample and a control group were followed to adulthood in a prospective longitudinal study. At age 31, participants completed a behaviorally specific questionnaire on experiences of sexual abuse and questionnaires on disclosure experiences and social reactions to disclosure. Due to low endorsement of sexual victimization among male participants and low sample size, results are reported for women only and exclude nine participants with speech disorder without LD. Participation rates were 28 of 40 in the LD cohort and 45 of 51 controls. Sexual victimization severity was defined using an index combining five indicators (duration, invasiveness, relationship to perpetrator, coercive tactics used, and number of perpetrators). Subthreshold sexual victimization was defined as a single, noncontact incident with a perpetrator unknown to the child; experiences with greater severity were classified as child sexual abuse.

RESULTS

Among women who reported sexual victimization by age 18, invasiveness and overall severity were greater in the LD cohort than in the control cohort. Women in the LD cohort (43%) were more likely than controls (16%) to report child sexual abuse, excluding subthreshold experiences. There were no differences between cohorts in probability of disclosure, latency to disclosure, or social reactions.

CONCLUSIONS

Women with a history of child LD in a nonclinical sample reported substantial child sexual abuse experiences. Implications for understanding associations between LD and mental health and for prevention and early intervention are discussed.

Excess BMP Signaling in Heterotopic Cartilage Forming in Prg4-null TMJ Discs

Heterotopic cartilage develops in certain pathologic conditions, including those affecting the human temporomandibular joint (TMJ), but the underlying molecular mechanisms remain obscure. This is in part due to the fact that a reliable animal model of such TMJ diseases is not available. Here, we show that aberrant chondrocyte differentiation and ectopic cartilage formation occur spontaneously in proteoglycan 4 (Prg4) mutant TMJ discs without further invasive procedure. By 2 mo of age, mutant disc cells displayed chondrocyte transdifferentiation, accompanied by strong expression of cartilage master gene Sox9 and matrix genes aggrecan and type II collagen. By 6 mo, heterotopic cartilage had formed in the discs and expressed cartilage hypertrophic markers Runx2 and ColX. The ectopic tissue grew in size over time and exhibited regional mineralization by 12 mo. Bone morphogenetic protein (BMP) signaling was activated with the ectopic chondrogenic cells and chondrocytes, as indicated by phosphorylated Smad 1/5/8 nuclear staining and by elevated expression of Bmp2, Bmpr1b, Bmpr2, and BMP signaling target genes. Likewise, we found that upon treatment with recombinant human BMP 2 in high-density micromass culture, mutant disc cells differentiated into chondrocytes and synthesized cartilage matrix more robustly than control cells. Importantly, a specific kinase inhibitor of BMP receptors drastically attenuated chondrogenesis in recombinant human BMP 2-treated mutant disc cultures. Unexpectedly, we found that Prg4 was expressed at joint-associated sites, including disc/muscle insertion and muscle/bone interface, and all these structures were abnormal in Prg4 mutants. Our data indicate that Prg4 is needed for TMJ disc integrity and function and that its absence leads to ectopic chondrogenesis and cartilage formation in conjunction with abnormal BMP signaling. Our findings imply that the BMP signaling pathway could be a potential therapeutic target for prevention or inhibition of ectopic cartilage formation in TMJ disease.

Lubricin is Required for the Structural Integrity and Post-natal Maintenance of TMJ

The Proteoglycan 4 (Prg4) product lubricin plays essential roles in boundary lubrication and movement in limb synovial joints, but its roles in temporomandibular joint (TMJ) are unclear. Thus, we characterized the TMJ phenotype in wild-type and Prg4(-/-) mouse littermates over age. As early as 2 weeks of age, mutant mice exhibited hyperplasia in the glenoid fossa articular cartilage, articular disc, and synovial membrane. By 1 month of age, there were fewer condylar superficial tenascin-C/Col1-positive cells and more numerous apoptotic condylar apical cells, while chondroprogenitors displayed higher mitotic activity, and Sox9-, Col2-, and ColX-expressing chondrocyte zones were significantly expanded. Mutant subchondral bone contained numerous Catepsin K-expressing osteoclasts at the chondro-osseous junction, increased invasive marrow cavities, and suboptimal subchondral bone. Mutant glenoid fossa, disc, synovial cells, and condyles displayed higher Hyaluronan synthase 2 expression. Mutant discs also lost their characteristic concave shape, exhibited ectopic chondrocyte differentiation, and occasionally adhered to condylar surfaces. A fibrinoid substance of unclear origin often covered the condylar surface. By 6 months of age, mutant condyles displayed osteoarthritic degradation with apical/mid-zone separation. In sum, lubricin exerts multiple essential direct and indirect roles to preserve TMJ structural and cellular integrity over post-natal life.

TMJ degeneration in SAMP8 mice is accompanied by deranged Ihh signaling

The temporomandibular joint (TMJ) functions as a load-bearing diarthrodial joint during mastication, and its continuous use and stress can lead to degeneration over age. Using senescence-accelerated (SAMP8) mice that develop early osteoarthritis-like changes in synovial joints at high frequency, we analyzed possible molecular mechanisms of TMJ degeneration and tested whether and how malocclusion may accelerate it. Condylar articular cartilage in young SAMP8 mice displayed early-onset osteoarthritic changes that included reductions in superficial/chondroprogenitor cell number, proteoglycan/collagen content, and Indian hedgehog (Ihh)-expressing chondrocytes. Following malocclusion induced by tooth milling, the SAMP8 condyles became morphologically defective, displayed even lower proteoglycan levels, and underwent abnormal chondrocyte maturation compared with malocclusion-treated condyles in wild-type mice. Malocclusion also induced faster progression of pathologic changes with increasing age in SAMP8 condyles as indicated by decreased PCNA-positive proliferating chondroprogenitors and increased TUNEL-positive apoptotic cells. These changes were accompanied by steeper reductions in Ihh signaling and by expression of matrix metalloproteinase 13 at the chondro-osseous junction in SAMP8 articular cartilage. In sum, we show for the first time that precocious TMJ degeneration in SAMP8 mice is accompanied by--and possibly attributable to--altered Ihh signaling and that occlusal dysfunction accelerates progression toward degenerative TMJ disease in this model.

Muenke syndrome mutation, FgfR3P²⁴⁴R, causes TMJ defects

Muenke syndrome is characterized by various craniofacial deformities and is caused by an autosomal-dominant activating mutation in fibroblast growth factor receptor 3 (FGFR3(P250R) ). Here, using mice carrying a corresponding mutation (FgfR3(P244R) ), we determined whether the mutation affects temporomandibular joint (TMJ) development and growth. In situ hybridization showed that FgfR3 was expressed in condylar chondroprogenitors and maturing chondrocytes that also expressed the Indian hedgehog (Ihh) receptor and transcriptional target Patched 1(Ptch1). In FgfR3(P244R) mutants, the condyles displayed reduced levels of Ihh expression, H4C-positive proliferating chondroprogenitors, and collagen type II- and type X-expressing chondrocytes. Primary bone spongiosa formation was also disturbed and was accompanied by increased osteoclastic activity and reduced trabecular bone formation. Treatment of wild-type condylar explants with recombinant FGF2/FGF9 decreased Ptch1 and PTHrP expression in superficial/polymorphic layers and proliferation in chondroprogenitors. We also observed early degenerative changes of condylar articular cartilage, abnormal development of the articular eminence/glenoid fossa in the TMJ, and fusion of the articular disc. Analysis of our data indicates that the activating FgfR3(P244R) mutation disturbs TMJ developmental processes, likely by reducing hedgehog signaling and endochondral ossification. We suggest that a balance between FGF and hedgehog signaling pathways is critical for the integrity of TMJ development and for the maintenance of cellular organization.

TMJ development and growth require primary cilia function

Primary cilia regulate limb and axial skeletal formation and hedgehog signaling, but their roles in temporomandibular joint (TMJ) development are unknown. Thus, we created conditional mouse mutants deficient in ciliary transport protein Kif3a in cartilage. In post-natal wild-type mice, primary cilia were occasionally observed on the superior, inferior, or lateral side of condylar cells. Cilia were barely detectable in mutant chondrocytes but were evident in surrounding tissues, attesting to the specificity of chondrocyte Kif3a ablation. Mutant condyles from 3-month-old mice were narrow and flat along their antero-posterior and medio-lateral axes, were often fused with the articular disc, and displayed an irregular bony surface. The polymorphic layer in P15 mutants contained fewer Sox9-expressing chondroprogenitor cells because of reduced mitotic activity, and newly differentiated chondrocytes underwent precocious hypertrophic enlargement accompanied by early activation of Indian hedgehog (Ihh). Interestingly, there was excessive intramembranous ossification along the perichondrium, accompanied by local expression of the hedgehog receptor Patched-1 and up-regulation of Osterix and Collagen I. In summary, Kif3a and primary cilia are required for coordination of chondrocyte maturation, intramembranous bone formation, and chondrogenic condylar growth. Defects in these processes in Kif3a condylar cartilage are likely to reflect abnormal hedgehog signaling topography and dysfunction.

Ihh signaling regulates mandibular symphysis development and growth

Symphyseal secondary cartilage is important for mandibular development, but the molecular mechanisms underlying its formation remain largely unknown. Here we asked whether Indian hedgehog (Ihh) regulates symphyseal cartilage development and growth. By embryonic days 16.5 to 18.5, Sox9-expressing chondrocytes formed within condensed Tgfβ-1/Runx2-expressing mesenchymal cells at the prospective symphyseal joint site, and established a growth-plate-like structure with distinct Ihh, collagen X, and osteopontin expression patterns. In post-natal life, mesenchymal cells expressing the Ihh receptor Patched1 were present anterior to the Ihh-expressing secondary cartilage, proliferated, differentiated into chondrocytes, and contributed to anterior growth of alveolar bone. In Ihh-null mice, however, symphyseal development was defective, mainly because of enhanced chondrocyte maturation and reduced proliferation of chondroprogenitor cells. Proliferation was partially restored in dual Ihh;Gli3 mutants, suggesting that Gli3 is normally a negative regulator of symphyseal development. Thus, Ihh signaling is essential for symphyseal cartilage development and anterior mandibular growth.

Sulfotransferase Ndst1 is needed for mandibular and TMJ development

Heparan sulfate proteoglycans (HS-PGs) regulate several developmental processes, but their possible roles in mandibular and TMJ formation are largely unclear. To uncover such roles, we generated mice lacking Golgi-associated N-sulfotransferase 1 (Ndst1) that catalyzes sulfation of HS-PG glycosaminoglycan chains. Ndst1-null mouse embryos exhibited different degrees of phenotypic penetrance. Severely affected mutants lacked the temporomandibular joint and condyle, but had a mandibular remnant that displayed abnormal tooth germs, substandard angiogenesis, and enhanced apoptosis. In mildly affected mutants, the condylar growth plate was dysfunctional and exhibited thicker superficial and polymorphic cell zones, a much wider distribution of Indian hedgehog signaling activity, and ectopic ossification along its lateral border. Interestingly, mildly affected mutants also exhibited facial asymmetry resembling that seen in individuals with hemifacial microsomia. Our findings indicate that Ndst1-dependent HS sulfation is critical for mandibular and TMJ development and allows HS-PGs to exert their roles via regulation of Ihh signaling topography and action.

Indian hedgehog roles in post-natal TMJ development and organization

Indian hedgehog (Ihh) is essential for embryonic mandibular condylar growth and disc primordium formation. To determine whether it regulates those processes during post-natal life, we ablated Ihh in cartilage of neonatal mice and assessed the consequences on temporomandibular joint (TMJ) growth and organization over age. Ihh deficiency caused condylar disorganization and growth retardation and reduced polymorphic cell layer proliferation. Expression of Sox9, Runx2, and Osterix was low, as was that of collagen II, collagen I, and aggrecan, thus altering the fibrocartilaginous nature of the condyle. Though a disc formed, it exhibited morphological defects, partial fusion with the glenoid bone surface, reduced synovial cavity space, and, unexpectedly, higher lubricin expression. Analysis of the data shows, for the first time, that continuous Ihh action is required for completion of post-natal TMJ growth and organization. Lubricin overexpression in mutants may represent a compensatory response to sustain TMJ movement and function.

Bipyridine derivatives at a solid/liquid interface: effects of the number and length of peripheral alkyl chains

Bipyridine derivatives (bpys) with various number and length of peripheral alkyl chains (with carbon numbers of n = 11-17) were synthesized, and their self-assembled monolayers were observed by scanning tunneling microscopy (STM) at a 1-phenyloctane/highly oriented pyrolytic graphite (HOPG) interface. The effects of the number, the substitution position, and the length of alkyl chains on the two-dimensional structures were systematically studied. Bpys substituted by a single alkyl chain in the p-position on each side adopted an almost linear form with zigzag-type alignment of the pi-conjugated unit, whereas, in the case of m-substitution, the bpys showed Z-shaped morphology with interdigitated alkyl chains. In both cases, no odd-even alkyl chain length effects were observed. The bpys with double alkyl chains at m- and p-positions displayed odd-even alkyl chain effects, suggesting that the formation of two-dimensional structure is dominated by the interactions between alkyl chains. Bpys with triple alkyl chains at o-, m-, and p-positions also showed odd-even alkyl chain effects, but only for the higher number of carbon atoms in the alkyl chain unit (n = 14-17). These results indicate that concerted intermolecular interactions of the alkyl chain unit introduce the odd-even chain length effect on the self-assembled two-dimensional structure. After coordination of PdCl(2), odd-even effects were quenched, and bpys were converged into the same lamellar structure, in which the molecules are almost linear. All the structural differences due to the odd-even alkyl chain length effect were explained in terms of intermolecular and molecule-substrate interactions.

Emerging adult outcomes of adolescent psychiatric and substance use disorders

This study investigates the age 25 outcomes of late adolescent mental health and substance use disorders. A hierarchical cluster analysis of age 19 DSM-III-R mental health and substance diagnoses placed participants into one of 9 clusters: Anxious, Depressed, Antisocial, Drug Abuser, Problem Drinker, Anxious Drinker, Depressed Drug Abuser and Antisocial Drinker, and No Diagnosis. Diagnoses were generated from the University of Michigan Composite International Diagnostic Interview. Repeated measures multivariate analyses of variance revealed distinct trajectories of improvement and decline among the 9 clusters. Clusters with co-occurring substance and mental health disorders improved over adolescent levels, but continued to have higher levels of depression symptoms, poorer global functioning, and higher levels of substance use than the No Diagnosis cluster. Members of the The Problem Drinkers cluster, who tended to have alcohol use disorders only at age 19, did not differ from their peers with no diagnoses. Drug use disorders in adolescence, with or without a co-occurring mental health disorders, were associated with a poor prognosis in emerging adulthood. Clinical interventions should distinguish among these diverse clinical presentations.

Roles of the primary cilium component Polaris in synchondrosis development

Primary cilia regulate several developmental processes and mediate hedgehog signaling. To study their roles in cranial base development, we created conditional mouse mutants deficient in Polaris, a critical primary cilium component, in cartilage. Mutant post-natal cranial bases were deformed, and their synchondrosis growth plates were disorganized. Expression of Indian hedgehog, Patched-1, collagen X, and MMP-13 was reduced and accompanied by decreases in endochondral bone. Interestingly, there was excessive intramembranous ossification along the perichondrium, accompanied by excessive Patched-1 expression, suggesting that Ihh distribution was wider and responsible for such excessive response. Indeed, expression of heparan sulfate proteoglycans (HS-PGs), normally involved in restricting hedgehog distribution, was barely detectable in mutant synchondroses. Analyses of the data provides further evidence for the essential roles of primary cilia and hedgehog signaling in cranial base development and chondrocyte maturation, and point to a close interdependence between cilia and HS-PGs to delimit targets of hedgehog action in synchondroses.

Development of phonological awareness in bilingual chinese children

This study investigated the phonological awareness of 219 first, second, and fourth grade Cantonese-speaking children from the south of China, who received immersion Mandarin instruction beginning in the first grade. Children received onset, rime and tone awareness tasks in Cantonese and Mandarin. Children performed better on the Cantonese onset awareness task in grade one, but the difference disappeared in higher grades. However, their performance on the rime and tone awareness tasks was better in Mandarin. These results reflect the phonological structure of the two languages: Mandarin has a more complex onset system, whereas Cantonese has more complex tone and rime systems. Moreover, children's phonological awareness increased faster in Mandarin, which likely resulted from Mandarin instruction. Confirmatory factor analysis suggested that onset-rime awareness is a universal construct, whereas tone awareness is a language-specific construct.

Models and determinants of vocabulary growth from kindergarten to adulthood

BACKGROUND

Increasing evidence suggests that childhood language problems persist into early adulthood. Nevertheless, little is known about how individual and environmental characteristics influence the language growth of individuals identified with speech/language problems.

METHOD

Individual growth curve models were utilised to examine how speech/language impairment and environmental variables (socioeconomic status, family separation, and maternal factors) influence vocabulary development from age 5 to 25. Participants were taken from a community sample of children initially diagnosed with speech/language problems at age 5 and their sex- and age-matched controls.

RESULTS

The language impaired group had significantly poorer receptive vocabulary than the speech impaired and control groups throughout the 20-year period. Family income was a significant predictor of vocabulary growth when considered separately, but ceased to be a predictor when language impairment status was taken into account. Maternal education and family separation were determinants of vocabulary at age 5, over and above language impairment status.

CONCLUSION

Language impairment is a significant risk factor for vocabulary development from childhood to adulthood. Individuals with speech impairment were less impaired on receptive vocabulary than individuals with language impairment. Further investigation into maternal and familial risk factors may provide targets for early intervention with children at risk for language impairment.

Wnt/beta-catenin signaling regulates cranial base development and growth

Wnt proteins and beta-catenin signaling regulate major processes during embryonic development, and we hypothesized that they regulate cranial base synchondrosis development and growth. To address this issue, we analyzed cartilage-specific beta-catenin-deficient mice. Mutant synchondroses lacked typical growth plate zones, and endochondral ossification was delayed. In reciprocal transgenic experiments, cartilage overexpression of a constitutive active Lef1, a transcriptional mediator of Wnt/beta-catenin signaling, caused precocious chondrocyte hypertrophy and intermingling of immature and mature chondrocytes. The developmental changes seen in beta-catenin-deficient synchondroses were accompanied by marked reductions in Ihh and PTHrP as well as sFRP-1, an endogenous Wnt signaling antagonist and a potential Ihh signaling target. Thus, Wnt/beta-catenin signaling is essential for cranial base development and synchondrosis growth plate function. This pathway promotes chondrocyte maturation and ossification events, and may exert this important role by dampening the effects of Ihh-PTHrP together with sFRP-1.

Expression of HIF prolyl hydroxylase isozymes in growth plate chondrocytes: relationship between maturation and apoptotic sensitivity

The overall goal of the current study was to examine the functional activity of the prolyl hydroxylases (PHDs) in maturing chondrocytes. Herein, we show for the first time that the PHDs are expressed in the maturing zone of the growth plate, and by a chondrocytic cell line. We determined if this protein and its substrate, hypoxia inducible factor (HIF)-1alpha, modulated the induction of apoptosis. Using a chondrocyte cell line that matured in culture, we inhibited HIF-1alpha expression using siRNA technology and pharmacologically blocked PHD activity. We noted that PHD suppression sensitized the cells to an apoptotic challenge with H(2)O(2). We next examined the interplay between the PHDs and HIF-1alpha by suppressing HIF-1alpha and blocking PHD activity. We noted reduced killing when the mature HIF-silenced cells were challenged with H(2)O(2). In contrast, there was limited change in the viability of immature cells. Based on these differences in chondrocyte susceptibility, it is concluded that HIF-1alpha sensitizes maturing cells to H(2)O(2)-mediated killing. We next determined if this change in the viability of the PHD-inhibited cells was linked to changes in activation of caspase-3. It was noted that there was a minimal change in enzyme activity of the PHD-inhibited HIF-1alpha suppressed cells. Finally, we found that as the chondrocytes mature, the activities of catalase and SOD were significantly reduced and that there was a decrease in the levels of Bcl-2 and Bcl(XL). This loss of protective activity together with the changes mediated by HIF would be expected to generate conditions that would favor the induction of chondrocyte apoptosis.

Odd–even effect and metal induced structural convergence in self-assembled monolayers of bipyridine derivatives

Scanning tunneling microscopy (STM) observations reveal that bipyridine derivatives which exhibit various two-dimensional structures due to the odd-even chain length effect are converged into a lamellar structure upon metal coordination.

Two-dimensional structure control by molecular width variation with metal coordination

The self-assembled monolayer of bipyridine derivative 1, which has two alkyl chains on each end, at the HOPG/1-phenyloctane interface was studied by in situ scanning tunneling microscopy (STM). The detailed mechanism of a spontaneous change in the monolayer packing pattern by Pd coordination was studied. Uncomplexed 1 existed in a bent form in the monolayer, and the alkyl chains were interdigitated, whereas Pd-complexed 1 was in a straight form and the alkyl chains were not interdigitated. An intermediate state of 1 was successfully observed during metal coordination. The structure was the bent form with noninterdigitated alkyl chains. Equilibrium intermolecular distances reported from ab initio calculations indicate that the molecular width of the central aromatic part of uncomplexed 1 (7.5 A) is substantially smaller than that of the peripheral alkyl chain part (9.2 A). The bent form was suitable for covering up the surface to maximize the packing density. However, the molecular width of the aromatic unit of Pd-complexed 1 (9.1 A) was almost identical to that of the alkyl chain unit (9.2 A). Therefore, Pd-complexed 1 took the straight form in the monolayer. The observation of surface coverage by STM suggests that the bent form increases the packing density by as much as 16% compared with that of the straight form. These results indicate that the control of molecular width can be used to design molecular templates for nanostructure formation.

Surface Potential Switching by Metal Ion Complexation/Decomplexation Using Bipyridinethiolate Monolayers on Gold

Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2'-bipyridine-5'-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method.

[3]Rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure

A novel [3]rotaxane composed of two 25-membered crownophanes and one axle molecule having two anthryl end groups was successfully synthesized via covalent bond formation followed by aminolysis, and can incorporate caesium ion into the space between the two macrocycles as a 1 : 1 sandwich-type complex, whereas it makes a 1 : 2 complex with lithium ion.

Synthesis of [1]rotaxane via covalent bond formation and its unique fluorescent response by energy transfer in the presence of lithium ion

Although there have been a lot of reports on the synthesis and properties of [n]rotaxanes (mainly n = 2), only a few reports on the synthesis of [1]rotaxane has been published by Vögtle's group and others (see ref 5). Generally speaking, [1]rotaxane might be expected to exhibit properties different from other rotaxanes, because the rotor and the axle in the [1]rotaxane is bound covalently and closely. We report on a novel method to make [1]rotaxanes via covalent bond formation from a macrocyclic compound. That is, we first prepared a bicyclic compound from macrocycle and then proceeded to [1]rotaxane by aminolysis. This is the first synthetic example of preparation of [1]rotaxane via covalent bond formation, not utilizing weak interactions such as hydrogen bonding, charge transfer, via metal complexation, etc. This method might provide a powerful and new tool for construction of [1]rotaxane as a new supramolecular system. In addition, we investigated energy transfer from rotor to axle using [1]rotaxane that we prepared. Energy transfer occurred perfectly from the naphthalene ring of the rotor to the anthracene ring of the axle. We found also that only lithium ion among alkali ions can drastically enhance the fluorescence intensity. This finding could be applicable to ion-sensing systems, switching devices, and so on.

Over- and ectopic expression of Wnt3 causes progressive loss of ameloblasts in postnatal mouse incisor teeth

Intercellular signaling is essential for the development of teeth during embryogenesis and in maintenance of the continuously growing incisor teeth in postnatal rodents. WNT intercellular signaling molecules have been implicated in the regulation of tooth development, and the Wnt3 gene shows specific expression in the enamel knot at the cap stage. We demonstrate here that Wnt3 also is expressed in specific epithelial cell layers in postnatal incisor teeth. To begin to delineate the functions of Wnt3 in developing and postnatal teeth, we determined the effects of over- and ectopic expression of Wnt3 in the tooth epithelium of mice carrying a keratin 14-Wnt3 transgene. Expression of the transgene caused a progressive loss of ameloblasts from postnatal lower incisor teeth. Loss of ameloblasts may be due to defective proliferation or differentiation of ameloblast precursors, progressive apoptosis of ameloblasts, or loss of ameloblast stem cells.