The silicone metacarpophalangeal joint arthroplasty: An in-vitro analysis

BACKGROUND

Silicone is still the gold standard implant in metacarpophalangeal arthroplasty. Whereas the clinical results are acceptable, in follow-ups with >10 years, high rates of implant fracture are common, and 5 to 7% of implants required revision. This work's purpose is to analyse the hypothesis that the joint flexion amplitude has a relevant effect on bone strain level, implant stress and bone-implant micromotion, which can reflect an increase in the risk of bone resorption/fatigue failure, implant fracture and osteolysis.

METHODS

To experimentally predict the cortical loading behaviour, composite metacarpals and proximal phalanges were used in intact and implanted states. A finite element model was developed to evaluate the structural behaviour of cancellous bone and implant. This model was validated by comparing cortical strain and load-displacement curve with experimental measurements.

FINDINGS

Bone strain changes between the intact and the implanted states showed a load transfer effect from the cortical to the cancellous bone that increases significantly with the flexion's amplitude rise. The peak implant stress occurred in the flexion amplitudes further away from the implant neutral angle. The highest implant pistoning motion and the highest phalanx cancellous-bone strain occurred simultaneously at the maximum flexion amplitude.

INTERPRETATION

Limiting joint flexion range will be helpful to reduce the strain-shielding effect on cortical bone, minimizing the overload effect on cancellous bone and decreasing the stress levels and the pistoning motion on the implant, ultimately contributing to the longevity of silicone arthroplasty.

Does Acid Etching Influence the Adhesion of Universal Adhesive Systems in Noncarious Cervical Lesions? A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the adhesion of universal adhesive systems to the dentin of noncarious cervical lesions (NCCLs) by comparing the etch-and-rinse and self-etch strategies through a systematic review and meta-analysis.

METHODS

Systematic electronic searches were performed by two independent reviewers into the following databases: PubMed/MEDLINE, Scopus, Web of Science, and Cochrane Library until December of 2021. Only randomized clinical trials were selected, comparing etch-and-rinse and self-etch strategies and using universal adhesive systems in NCCLs. This systematic review was conducted according to the PRISMA guidelines and registered into PROSPERO.

RESULTS

After the removal of duplicates, 170 articles were identified. In an initial screening of titles and abstracts, 146 records did not satisfy the inclusion criteria and were, therefore, excluded. Twenty-four studies were eligible for evaluation of the full text, and four were excluded after this step. Finally, 20 randomized clinical trials were included in this systematic review and meta-analysis.

CONCLUSION

This systematic review and meta-analysis revealed that applying universal adhesive systems in the etch-and-rinse strategy could lead to better medium-term (>12 to 36 months) retention of NCCL restorations than the self-etch strategy, as well as resulting in lower percentages of marginal discoloration, marginal adaptation, and secondary caries. However, the use of a self-etching strategy can lead to lower postoperative sensitivity.

A64 THE DIETARY FIBRE RHAMNOGALACTURONAN PROMOTES INTESTINAL EPITHELIAL CELL MIGRATION THROUGH THE NF-κB SIGNALING PATHWAY

Background

Damaged intestinal epithelial barrier is characteristic of inflammatory bowel diseases (IBD) and mucosal healing is the primary goal for IBD treatment. We previously showed the direct beneficial effects of rhamnogalacturonan (RGal), a polysaccharide isolated from the plant Acmella oleracea, on intestinal epithelial barrier function with participation of TLR4 and PKC activation. We also observed that RGal accelerates wound healing in human colonic epithelial Caco-2 cells. RNAseq data and pathway analysis have indicated the involvement of the canonical nuclear factor kB (NF-kB) signaling pathway.

Aims

We hypothesize that RGal increases intestinal epithelial wound healing through NF-kB signaling pathway.

Methods

Caco-2 cells monolayers were scratched and treated with vehicle (media or 0.5% DMSO in media) or RGal (1000 mg/ml) for 48 h. Wound healing was assessed using the IncuCyte live cell imaging system. Proliferation and apoptosis of cells were evaluated using EdU and TUNEL assays, respectively. Inhibitors were added at the same time (transcription inhibitor Actinomycin D, 5 mg/ml) or 1 h (NF-kB inhibitors Bay 11–7082 and JSH-23, 10 and 20 mM, respectively, or COX-2 inhibitor NS-398, 20 mM) before RGal treatment. Unwounded Caco-2 monolayers treated with RGal (1000 mg/ml) were collected for Western blotting for COX-2 protein.

Results

In the wound healing assay, RGal at a concentration of 1000 µg/ml enhanced wound healing by 12.5% at 48 h compared to control group, under 10% serum conditions. Neither proliferation nor apoptosis were involved in the RGal effect on wound healing, suggesting the response was due solely to cell migration. Actinomycin D (5 mg/ml), Bay 11–7082 (10 mM) or JSH-23 (20 mM) treatment significantly reversed the effect of RGal on wound healing, showing that the response was transcriptionally dependent and involved NF-kB signaling. Treatment of cells with NS-398 (20 mM) also reversed the effect of RGal on wound healing. COX-2 protein expression was significantly increased at 6 and 12 h after RGal addition to Caco-2 monolayers.

Conclusions

These data suggest that the plant-based polysaccharide RGal increases intestinal epithelial cell wound healing by increasing cell migration. The RGal effect is dependent on the activation of the transcription factor NF-kB and downstream COX-2 protein expression and activity. Our findings show a novel mechanism of action of RGal in wound healing that could help in the resolution of intestinal inflammation and mucosal healing.

Funding Agencies

NSERC

Salbutamol tolerability and efficacy in patients with spinal muscular atrophy type II

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by homozygous deletions or loss-of-function mutations in SMN1, which result in a degeneration of motor neurons in the spinal cord and brain stem. Even without a randomized placebo-controlled trial, salbutamol has been offered to patients with SMA in the neuromuscular clinics of most of hospitals for many years. We describe the response to salbutamol in 48 patients with SMA type II who were not taking any other medication. We investigate the changes over an eighteen-month period in motor functional scales and we analyze side effects and subjective response to treatment. Our results suggest that oral administration of salbutamol might be helpful in the maintenance of motor function in patients with SMA type II. An apparent beneficial effect was observed in functional scales of children under the age of 6, especially during the first 6 months of therapy. The majority of patients of all ages referred some kind of subjective positive effect associated with therapy intake. Salbutamol seemed safe and was well tolerated without serious side effects.

Biomechanical analysis of metacarpophalangeal joint arthroplasty with metal-polyethylene implant: An in-vitro study

BACKGROUND

The most common implant options for the metacarpophalangeal joint arthroplasty include silicone, pyrocarbon and metal-polyethylene. A systematic review of outcomes of silicone and pyrocarbon implants was conducted; however, a similar exercise for metal-polyethylene implants revealed a scarcity of published results and lack of long-term follow-up studies. The aim of the present work is to test the hypothesis that the magnitude of metacarpophalangeal joint cyclic loads generates stress and strain behaviour, which leads to long-term reduced risk of metal-polyethylene component loosening.

METHODS

This study was performed using synthetic metacarpals and proximal phalanges to experimentally predict the cortex strain behaviour for both intact and implanted states. Finite element models were developed to assess the structural behaviour of cancellous-bone and metal-polyethylene components; these models were validated by comparing cortex strains predictions against the measurements.

FINDINGS

Cortex strains in the implanted metacarpophalangeal joint presented a significant reduction in relation to the intact joint; the exception was the dorsal side of the phalanx, which presents a significant strain increase. Cancellous-bone at proximal dorsal region of phalanx reveals a three to fourfold strain increase as compared to the intact condition. Interpretation The use of metal-polyethylene implant changes the strain behaviour of the metacarpophalangeal joint yielding the risk of cancellous-bone fatigue failure due to overload in proximal phalanx; this risk is more important than the risk of bone-resorption due to the strain-shielding effect. By limiting the loads magnitude over the joint after arthroplasty, it may contribute to the prevention of implant loosening.

Hepatic injury induced by thioacetamide causes aortic endothelial dysfunction by a cyclooxygenase-dependent mechanism

Liver cirrhosis is associated with a wide range of cardiovascular abnormalities including hyperdynamic circulation and cirrhotic cardiomyopathy. The pathogenic mechanisms of these cardiovascular changes are multifactorial and include vascular dysregulations.

AIM

The present study tested the hypothesis that the systemic vascular hyporesponsiveness in thioacetamide (TAA)-induced liver injury model is dependent on nitric oxide (NO) and cyclooxygenase (COX) derivatives.

MAIN METHODS

Wistar rats were treated with TAA for eight weeks to induce liver injury.

KEY FINDINGS

The maximal contractile response in concentration-effect curves to phenylephrine was decreased in aorta from TAA-treated rats, but no differences were found in aorta without endothelium, suggesting an endothelium-dependent mechanism in decreased contractile response. There was no difference in the contractile response with and without L-NAME (N(ω)-nitro-l-arginine methyl ester) in rats with liver injury, showing that the TAA treatment impairs NO synthesis. Pre-incubation of the aorta with indomethacin, a COX-inhibitor, normalized the reduced contractile response to phenylephrine in arteries from TAA group. Also, COX-2 and iNOS (inducible nitric oxide syntase) protein expression was increased in aorta from TAA group compared to control group. Animals submitted to TAA treatment had a reduction in systolic blood pressure. Our findings demonstrated that liver injury induced by TAA caused a decrease in aortic contractile response by a COX-dependent mechanism but not by NO release. Also, it was demonstrated an inflammatory process in the aorta of TAA-treated rats by increased expression of COX-2 and iNOS.

SIGNIFICANCE

Therefore, there is an essential contribution of COX-2 activation in extra-hepatic vascular dysfunction and inflammation present in cirrhosis induced by TAA.

[A new phenotype of infantile-onset Pompe disease]

INTRODUCTION

Infantile-onset Pompe disease is a kind of glycogenosis resulting from a deficit of the enzyme acid alpha-glucosidase. Before specific enzyme replacement therapy (ERT) became available, the classic form was fatal during the first two years of life. ERT increases survival and improves cardiac, respiratory and motor functioning.

CASE REPORTS

Case 1: 2-month-old infant with predominantly axial hypotonia who required the use of a nasogastric tube as a result of difficulties in sucking and swallowing. Myopathy and hypertrophic cardiomyopathy were observed. The patient was diagnosed with Pompe disease, ERT was established and improved heart and motor functioning were noted. Nevertheless, she presented recurring respiratory infections that finally made it necessary to perform a tracheostomy. She is currently still undergoing ERT, walks with a walker and presents a mild ventricular dysfunction. Case 2: 3-week-old infant who was taken to see his paediatrician for a routine check-up. The examination revealed a systolic bruit and axial and proximal hypotonia. Cardiology tests revealed hypertrophic cardiomyopathy. The patient was sent to a referral centre, where he was diagnosed with Pompe disease and a cross-reactive immunological material-negative status. The patient received immunomodulator treatment and ERT. Progress was favourable, although he presented frequent respiratory infections. The patient is currently capable of walking by himself, although the gait is unsteady.

CONCLUSIONS

Both cases illustrate the new phenotype of infantile-onset Pompe disease treated with ERT. Despite the motor limitations and respiratory involvement presented by the patients, both survival and autonomy have increased.

Biomechanical evaluation of pyrocarbon proximal interphalangeal joint arthroplasty: An in-vitro analysis

BACKGROUND

Pyrocarbon proximal interphalangeal joint arthroplasty provided patients with excellent pain relief and joint motion, however, overall implant complications have been very variable, with some good outcomes at short-medium-term follow-up and some bad outcomes at longer-term follow-up. Implant loosening with migration, dislocation and implant fracture were the main reported clinical complications. The aim of the present work was to test the hypothesis that the magnitude proximal interphalangeal joint cyclic loads in daily hand functions generates stress-strain behaviour which may be associated with a risk of pyrocarbon component loosening in the long-term.

METHODS

This study was performed using synthetic proximal and middle phalanges to experimentally predict the cortex strain behaviour and implant stability considering different load conditions for both intact and implanted states. Finite element models were developed to assess the structural behaviour of cancellous-bone and pyrocarbon components, these models were validated against experimentally measured cortex strains.

FINDINGS

Cortex strains showed a significant increase at dorsal side and reduction at palmar side between intact and implanted states. Cancellous-bone adjacent to the condylar implant base components suffers a two to threefold strain increase, comparing with the intact condition.

INTERPRETATION

The use of pyrocarbon implant changes the biomechanical behaviour of the joint phalanges and is associated with a potential risk of support cancellous-bone suffer fatigue failure in mid to long term due to the strain increase for cyclic loads in the range of daily hand activities, this risk is more prominent than the risk of bone resorption due to strain-shielding effect.

Molecular characterization of congenital myasthenic syndromes in Spain

Congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders, all of which impair neuromuscular transmission. Epidemiological data and frequencies of gene mutations are scarce in the literature. Here we describe the molecular genetic and clinical findings of sixty-four genetically confirmed CMS patients from Spain. Thirty-six mutations in the CHRNE, RAPSN, COLQ, GFPT1, DOK7, CHRNG, GMPPB, CHAT, CHRNA1, and CHRNB1 genes were identified in our patients, with five of them not reported so far. These data provide an overview on the relative frequencies of the different CMS subtypes in a large Spanish population. CHRNE mutations are the most common cause of CMS in Spain, accounting for 27% of the total. The second most common are RAPSN mutations. We found a higher rate of GFPT1 mutations in comparison with other populations. Remarkably, several founder mutations made a large contribution to CMS in Spain: RAPSN c.264C > A (p.Asn88Lys), CHRNE c.130insG (Glu44Glyfs*3), CHRNE c.1353insG (p.Asn542Gluf*4), DOK7 c.1124_1127dup (p.Ala378Serfs*30), and particularly frequent in Spain in comparison with other populations, COLQ c.1289A > C (p.Tyr430Ser). Furthermore, we describe phenotypes and distinguishing clinical signs associated with the various CMS genes which might help to identify specific CMS subtypes to guide diagnosis and management.

Strain shielding in distal radius after wrist arthroplasty with a current generation implant: An in vitro analysis

A systematic review of peer reviewed articles has shown that the main cause for wrist arthroplasty revision is carpal and radial prosthetic loosening and instability. To improve arthroplasty outcomes, successive generations of implants have been developed over time. The problem with the current generation of implants is the lack of long-term outcomes data. The aim of the present work was to test the hypothesis that the current generation Maestro WRS implant has a stress, strain and stability behaviour which may be associated with a reduced risk of long-term radial component loosening. This study was performed using synthetic radii to experimentally predict the cortex strain behaviour and implant stability considering different load conditions for both intact and implanted conditions. Finite element models were developed to assess the structural behaviour of cancellous-bone and bone-cement, these models were validated against experimentally measured cortex strains. Measured cortex strains showed a significant reduction between intact and implanted states. Cancellous bone adjacent to the radial body component suffers a two to threefold strain reduction, comparing with the intact condition, while along the radial stem, in the axial direction, a strain increase was observed. It is concluded that the use of contemporary Maestro WRS implant changes the biomechanical behaviour of the radius and is associated with a potential risk of bone resorption by stress-shielding in the distal radius region for wrist loads in the range of daily activities.

A statistical algorithm showing coenzyme Q10 and citrate synthase as biomarkers for mitochondrial respiratory chain enzyme activities

Laboratory data interpretation for the assessment of complex biological systems remains a great challenge, as occurs in mitochondrial function research studies. The classical biochemical data interpretation of patients versus reference values may be insufficient, and in fact the current classifications of mitochondrial patients are still done on basis of probability criteria. We have developed and applied a mathematic agglomerative algorithm to search for correlations among the different biochemical variables of the mitochondrial respiratory chain in order to identify populations displaying correlation coefficients >0.95. We demonstrated that coenzyme Q10 may be a better biomarker of mitochondrial respiratory chain enzyme activities than the citrate synthase activity. Furthermore, the application of this algorithm may be useful to re-classify mitochondrial patients or to explore associations among other biochemical variables from different biological systems.

Total arthroplasty of basal thumb joint with Elektra prothesis: an in vitro analysis

The reported outcomes of the Elektra thumb carpo-metacarpal joint implant have been very variable. This study evaluates the influence of daily cyclic loads and the type of the screw-fit cup insertion technique in the trapezium, with and without prior threading, on the structural bone behaviour. The study was performed experimentally to predict initial implant stability and cortical bone strains. Computational models were developed to assess the structural cancellous bone behaviour. The use of Elektra implant considerably changed the bone strain behaviour compared with the intact joint. This may be associated with risks of cancellous bone fatigue failure due to overload, particularly in the trapezium. The joint load magnitude has a more important structural role than that of the screw-fit cup insertion technique. Limiting the magnitude of thumb loads after arthroplasty may contribute positively to the longevity of this procedure.

LEVEL OF EVIDENCE

V.

[Clinical guidelines for infantile-onset Pompe disease]

Infantile-onset Pompe disease has a fatal prognosis in the short term unless it is diagnosed at an early stage and enzyme replacement therapy is not started as soon as possible. A group of specialists from different disciplines involved in this disease have reviewed the current scientific evidence and have drawn up an agreed series of recommendations on the diagnosis, treatment and follow-up of patients. We recommend establishing enzyme treatment in any patient with symptomatic Pompe disease with onset within the first year of life, with a clinical and enzymatic diagnosis, and once the CRIM (cross-reactive immunological material) status is known.

Phenotypic heterogeneity in two large Roma families with a congenital myasthenic syndrome due to CHRNE 1267delG mutation. A long-term follow-up

Congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders. Mutations in CHRNE are one of the most common cause of them and the ɛ1267delG frameshifting mutation is described to be present on at least one allele of 60% of patients with CHRNE mutations. We present a comprehensive description of the heterogeneous clinical features of the CMS caused by the homozygous 1267delG mutation in the AChR Ɛ subunit in nine members of two large Gipsy kindreds. Our observations indicate that founder Roma mutation 1267delG leads to a phenotype further characterized by ophthalmoplegia, bilateral ptosis, and good response to pyridostigmine and 3,4-DAP; but also by facial weakness, bulbar symptoms, neck muscle weakness, and proximal limb weakness that sometimes entails the loss of ambulation. Interestingly, we found in our series a remarkable proportion of patients with a progressive or fluctuating course of the disease. This finding is in some contrast with previous idea that considered this form of CMS as benign, non progressive, and with a low impact on the capacity of ambulation.

Genomic ancestry evaluated by ancestry-informative markers in patients with sickle cell disease

The β(s) mutation is responsible for the most aggressive form of sickle cell disease, has a predominantly African origin, and arrived in Brazil through the slave trade. However, the Brazilian population is highly miscegenated, underscoring the importance of ancestry-informative markers (AIMs) for the identification of the genetic structure of a population. In this study, we have estimated the genetic contributions of various ethnicities in individuals with sickle cell disease in the microregion of Jequié, Bahia, in Brazil, by using AIMs, and compared the findings to those from a phenotypic characterization. Eight AIMs were analyzed: AT3 (rs3138521), DRD2 (rs1079598), APO (rs3138522), PV92, Sb19.3 (rs3138524), CKM (rs4884), LPL (rs285), and CCR5Δ32 (rs333). Samples were subjected to polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism. The amplified products were electrophoresed on agarose gels, and the data were statistically analyzed using Genepop, FSTAT 2.9, and Admix3. Phenotypic classification showed a high frequency of mulattos  (85%) in the Brazilian population; however, ancestry-informative markers indicated that 44, 42, and 11% of the population had European, African, and native American ancestries, respectively. The phenotypic classification is justified as a complementary method for the characterization of the genetic ancestry in patients with sickle cell disease, as it confirms the molecular findings regarding ancestry.