Effect on enamel shear bond strength of adding microsilver and nanosilver particles to the primer of an orthodontic adhesive

Background

The objective of this study was to determine whether the addition of microsilver or nanosilver particles to an orthodontic primer affects shear bond strength (SBS) and bracket/adhesive failure.

Methods

Bovine incisors were randomly divided into six groups with 16 specimens in each: In group 1 (control), brackets were bonded with Transbond? XT primer. In the experimental groups, microsilver (groups 2 and 3) and nanosilver (groups 4–6) particles of different sizes were added to Transbond XT primer and light cured for 15 seconds [group 2: 0.1% (w/w) microsilver particle size 3.5–18 μm; group 3: 0.3% (w/w) microsilver particle size 3.5–18 μm; group 4: 0.11% (w/w) nanosilver particle size 12.6–18.5 nm; group 5: 0.18% (w/w) nanosilver particle size 12.6–18.5 nm; group 6: 0.33% (w/w) nanosilver particle size 12.6–18.5 nm]. Thereafter, brackets were bonded by light curing the adhesive for 20 seconds. After 24 hours of storage in distilled water at 37°C, SBS was measured with a Zwicki 1120 testing machine. The adhesive remnant index and the prevalence of silver spots on the specimen surface were determined under 10× magnification. Statistical two-way analysis of variance was performed to compare SBS, and a chi-square test was used to compare ARI scores and the prevalence of silver spots.

Results

No significant differences in SBS (control: 16.59?±?6.82 MPa; group 2: 20.6?±?4.19 MPa; group 3: 16.98?±?4.84 MPa; group 4: 17.15?±?5.92 MPa; group 5: 20.09?±?3.35 MPa; group 6: 16.44?±?4.51 MPa; p?>?0.665) and ARI scores (p?=?0.901) were found between the control group and any experimental group. Only experimental groups with nanosilver particles revealed statistically more silver spots on the remaining adhesive.

Conclusions

Addition of small concentrations of microsilver or nanosilver particles affects neither SBS nor ARI scores. Addition of nanosilver particles results in silver spots in the remaining primer visible under 10× magnification. Further studies are needed to investigate the anti-caries potential and clinical performance of conventional orthodontic primer with incorporated nanosilver or microsilver particles.

     

Control strategies for active lower extremity prosthetics and orthotics: a review

Technological advancements have led to the development of numerous wearable robotic devices for the physical assistance and restoration of human locomotion. While many challenges remain with respect to the mechanical design of such devices, it is at least equally challenging and important to develop strategies to control them in concert with the intentions of the user.This work reviews the state-of-the-art techniques for controlling portable active lower limb prosthetic and orthotic (P/O) devices in the context of locomotive activities of daily living (ADL), and considers how these can be interfaced with the user’s sensory-motor control system. This review underscores the practical challenges and opportunities associated with P/O control, which can be used to accelerate future developments in this field. Furthermore, this work provides a classification scheme for the comparison of the various control strategies.As a novel contribution, a general framework for the control of portable gait-assistance devices is proposed. This framework accounts for the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. Such a treatment of P/Os – not as independent devices, but as actors within an ecosystem – is suggested to be necessary to structure the next generation of intelligent and multifunctional controllers.Each element of the proposed framework is discussed with respect to the role that it plays in the assistance of locomotion, along with how its states can be sensed as inputs to the controller. The reviewed controllers are shown to fit within different levels of a hierarchical scheme, which loosely resembles the structure and functionality of the nominal human central nervous system (CNS). Active and passive safety mechanisms are considered to be central aspects underlying all of P/O design and control, and are shown to be critical for regulatory approval of such devices for real-world use.The works discussed herein provide evidence that, while we are getting ever closer, significant challenges still exist for the development of controllers for portable powered P/O devices that can seamlessly integrate with the user’s neuromusculoskeletal system and are practical for use in locomotive ADL.     

Function and regulation of self-reactive marginal zone B cells in autoimmune arthritis

Polyreactive innate-type B cells account for many B cells expressing self-reactivity in the periphery. Improper regulation of these B cells may be an important factor that underlies autoimmune disease. Here we have explored the influence of self-reactive innate B cells in the development of collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis. We show that splenic marginal zone (MZ), but not B-1 B cells exhibit spontaneous IgM reactivity to autologous collagen II in naïve mice. Upon immunization with heterologous collagen II in complete Freund''s adjuvant the collagen-reactive MZ B cells expanded rapidly, while the B-1 B cells showed a modest anti-collagen response. The MZ B cells were easily activated by toll-like receptor (TLR) 4 and 9-ligands in vitro, inducing proliferation and cytokine secretion, implying that dual engagement of the B-cell receptor and TLRs may promote the immune response to self-antigen. Furthermore, collagen-primed MZ B cells showed significant antigen-presenting capacity as reflected by cognate T-cell proliferation in vitro and induction of IgG anti-collagen antibodies in vivo. MZ B cells that were deficient in complement receptors 1 and 2 demonstrated increased proliferation and cytokine production, while Fcγ receptor IIb deficiency of the cells lead to increased cytokine production and antigen presentation. In conclusion, our data highlight self-reactive MZ B cells as initiators of the autoimmune response in CIA, where complement and Fc receptors are relevant in controlling the self-reactivity in the cells.     

Development and first data of a customized short tracheal cannula based on digital data

Purpose

At the moment, there is an inadequate margin fit of commercially available stoma buttons. The aim of the present study was to develop a customized short tracheal cannula based on digital data. Furthermore, the applied material has to be evaluated considering germ colonization and appropriate cleaning procedures.

Methods

Computed tomographies of 53 patients who underwent laryngectomy were surveyed. Based on the digital data, a customized short tracheal cannula was created and manufactured from silicone. The new cannula was incorporated in ten patients and worn for 4 weeks. A clinical examination of an otolaryngologist and subjective assessment of the patients were carried out. Furthermore, microbiological test considering germ colonization was performed.

Results

The customized short tracheal cannula could be incorporated in all patients. The clinical results showed no irritation or mucosal lesions. The subjective individual evaluation by the patients was promising. The proposals for improvement could be considered. The microbiological examination revealed a higher contamination of the silicone compared to the silver cannulas. Both chemical and mechanical decontamination showed sufficient results.

Conclusion

A workflow for development and manufacturing of a customized short tracheal cannula from digital data could be established. The cannula is compatible to standard equipment and routine cleaning procedures. Clinical studies are required to evaluate the potential benefit for patients.

     

Vitamin B6 in Primary Hyperoxaluria I: First Prospective Trial after 40 Years of Practice

Background and objectives

Primary hyperoxaluria type I (PH I) is caused by deficiency of the liver-specific enzyme alanine-glyoxylate:aminotransferase (AGT). Many mutations are known to perturb AGT protein folding. Vitamin B6 (B6) is the only specific drug available for treatment. Although B6 has been used for >40 years, controlled data on B6 efficacy are lacking. Therefore, this study investigated the absolute and relative change of urinary oxalate (Uox) excretion under increasing dosages of B6, the first prospective trial to do so.

Design, setting, participants, & measurements

B6 response was studied in 12 patients (7 male patients) with genetically confirmed PH I (3 Gly170Arg homozygous, 5 compound Gly170Arg and/or Phe152Ile heterozygous, and 4 negative for Gly170Arg and/or Phe152Ile mutations) and noncompromised renal function. Efficacy was defined as a 30% relative reduction in Uox excretion. B6 was administered orally starting at 5 mg/kg body weight per day and given in increments of 5 mg/kg every 6 weeks, up to a final dosage of 20 mg/kg per day at week 24. Uox and serum B6 levels were measured every 6 weeks.

Results

Mean relative Uox reduction was 25.5%. Uox declined from 2.09±0.55 (mean±SD) at baseline to 1.52±0.60 mmol/1.73 m² per day (P=0.01) at week 24. Serum B6 levels increased from 22.5±8.7 to 1217±776 ng/ml (P<0.001). Six patients showed a ≥30% relative reduction of Uox at week 24.

Conclusion

This first prospective trial confirmed B6 efficacy in 50% of patients (three of three homozygous, one of five heterozygous, and two of four patients negative for the Gly170Arg and/or Phe152Ile mutations). Interestingly, no complete biochemical remission was observed, even in the homozygous Gly170Arg study participants. Future trials are necessary to learn more about genotype-related B6 response and B6 metabolism.     

Controversial association results for INSIG2 on body mass index may be explained by interactions with age and with MC4R

Among the single-nucleotide polymorphisms (SNPs) previously reported to be associated with body mass index (BMI) and obesity, we focus on a common risk variant rs7566605 upstream of the insulin-induced gene 2 (INSIG2) gene and a rare protective variant rs2229616 on the melanocortin-4 receptor (MC4R) gene. INSIG2 is involved in adipogenesis and MC4R effects hormonal appetite control in response to the amount of adipose tissue. The influence of rs2229616 (MC4R) on BMI and obesity has been confirmed repeatedly and insight into the underlying mechanism provided. However, a main effect of rs7566605 (INSIG2) is under debate because of inconsistent replications of association. Interaction of rs7566605 with age may offer an explanation. SNP–age and SNP–SNP interaction models were tested on independent individuals from three population-based longitudinal cohorts, restricting the analysis to an observed age of 25–74 years. KORA S3/F3, KORA S4/F4 (Augsburg, Germany, 1994–2005, 1999–2008), and Framingham-Offspring data (Framingham, USA, 1971–2001) were analysed, with a total sample size of N=6926 in the joint analysis. The effect of interaction between rs7566605 and age on BMI and obesity status is significant and consistent across studies. This new evidence for rs7566605 (INSIG2) complements previous research. In addition, the interaction effect of rs7566605 with the MC4R variant rs2229616 on BMI was observed. This effect size was three times larger than that in a previously reported single-locus main effect of rs2229616. This leads to the conclusion that SNP–age or SNP–SNP interactions can mask genetic effects for complex diseases if left unaccounted for.     

Mutation of POC1B in a Severe Syndromic Retinal Ciliopathy

We describe a consanguineous Iraqi family with Leber congenital amaurosis (LCA), Joubert syndrome (JBTS), and polycystic kidney disease (PKD). Targeted next‐generation sequencing for excluding mutations in known LCA and JBTS genes, homozygosity mapping, and whole‐exome sequencing identified a homozygous missense variant, c.317G>C (p.Arg106Pro), in POC1B, a gene essential for ciliogenesis, basal body, and centrosome integrity. In silico modeling suggested a requirement of p.Arg106 for the formation of the third WD40 repeat and a protein interaction interface. In human and mouse retina, POC1B localized to the basal body and centriole adjacent to the connecting cilium of photoreceptors and in synapses of the outer plexiform layer. Knockdown of Poc1b in zebrafish caused cystic kidneys and retinal degeneration with shortened and reduced photoreceptor connecting cilia, compatible with the human syndromic ciliopathy. A recent study describes homozygosity for p.Arg106Pro_POC1B in a family with nonsyndromic cone‐rod dystrophy. The phenotype associated with homozygous p.Arg106Pro_POC1B may thus be highly variable, analogous to homozygous p.Leu710Ser in WDR19 causing either isolated retinitis pigmentosa or Jeune syndrome. Our study indicates that POC1B is required for retinal integrity, and we propose POC1B mutations as a probable cause for JBTS with severe PKD.