Results of patch testing 2-hydroxyethyl methacrylate (HEMA) in the European baseline series: A 4-year retrospective study

BACKGROUND

2-Hydroxyethyl methacrylate (HEMA) was added to the European baseline series (EBS) in 2019. Few recent data are available on the frequency and relevance of positive reactions to this hapten.

OBJECTIVES

To investigate the frequency and relevance of positive patch tests to HEMA in the EBS in a university hospital in Amsterdam, The Netherlands.

PATIENTS AND METHODS

Retrospective study in patients with positive patch tests to HEMA investigated between June 2019 and August 2023.

RESULTS

Of 2927 consecutive patients, 88 (79 women and 9 men; 3.0%) had a positive reaction to HEMA. The prevalence in women was 3.9%, in men 1.0%. Forty-three (49%) reactions were judged to be of current clinical relevance and 21 (24%) of past relevance. In this group of 64 patients with relevant reactions, 18 (28%) had occupational contact with (meth)acrylate-containing products, of who 11 (61%) were nail stylists. In 46 patients with non-occupational allergic contact dermatitis, 31 (67%) had allergic reactions to nail cosmetics. Glues and glue-containing products accounted for 22% of the materials causing allergic contact dermatitis and dental products for 8%.

CONCLUSIONS

Allergic reactions to HEMA are very frequent in women investigated in Amsterdam. Nearly two thirds of cases were caused by nail cosmetics.

New protocol to affix sample for environmental and high vacuum electron microscopy

Electron microscopy has become increasingly essential as an investigative research resource in various fields of science. Despite the evolution of the equipment and preparation techniques, little has been published on techniques for affixation and removal of samples on the stubs after analysis. This work aims to illustrate a quick and low-cost procedure for fixing and removing a sample from the support for analysis by electronic microscopy, applied to crustacean and insect species, as well as other invertebrates. It thus makes it feasible to use specimens or anatomical portions of specimens represented by a few individuals, or designated as paratypes or holotypes in a collection. RESEARCH HIGHLIGHTS: This study presents a quick and low-cost procedure for fixing and removing samples from support for electron microscopy analysis. This technique makes it possible to use individual specimens or anatomical portions represented in a collection. Fluidization of the adhesive and its complete removal allow easy recovery and repositioning of samples.

2-Hydroxyethyl methacrylate (HEMA): A clinical review of contact allergy and allergic contact dermatitis-Part 1. Introduction, epidemiology, case series and case reports

2-Hydroxyethyl methacrylate (HEMA) has been increasingly recognised as a contact allergen and was added to the European baseline series in 2019. In this article (2 parts), the results of an extensive literature review of the clinical aspects of contact allergy/allergic contact dermatitis to HEMA are presented. In part 1, the epidemiology of HEMA contact allergy is discussed and detailed information on published case series and case reports presented. HEMA is an important cause of contact allergy/allergic contact dermatitis in North America and Europe with recent prevalences of >3% in the USA + Canada and 1.5%-3.7% in Europe. Currently, most cases are caused by nail cosmetics, both in consumers and professional nail stylists. In our literature review, we have found 24 studies presenting case series of patients with allergic contact dermatitis attributed to HEMA and 168 case reports. However, the presence of HEMA in the products causing ACD was established in only a minority. Part 2 will discuss cross- and co-sensitisation, and other skin reactions to HEMA, will assess whether HEMA is the most frequent (meth)acrylate allergen and how sensitive HEMA as a screening agent is, investigate the presence of HEMA in commercial products and provide practical information on patch testing procedures.

Astrocytes: Lessons Learned from the Cuprizone Model

A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.

Selective Arterial Embolization of Ruptured Hepatocellular Carcinoma with N-Butyl Cyanoacrylate and Lipiodol: Safety, Efficacy, and Short-Term Outcomes

The rupture of hepatocellular carcinoma (rHCC) is uncommon but causes sudden life-threatening bleeding. Selective transarterial embolization (STAE) is an effective bleeding-control option. The optimal embolic agent is unknown, and data on the use of cyanoacrylate glue are lacking. The objective of this study was to report the outcomes of cyanoacrylate-lipiodol embolization for rHCC. We retrospectively reviewed the files of the 16 patients (14 males; mean age, 72 years) who underwent emergency cyanoacrylate-lipiodol STAE at a single center in 2012-2023 for spontaneous rHCC. All 16 patients had subcapsular HCC and abundant hemoperitoneum. The technical success rate was 94% (15/16). Day 30 mortality was 19%; the three patients who died had severe hemodynamic instability at admission; one death was due to rebleeding. Liver enzyme levels returned to baseline by day 30. No rebleeding was recorded during the median follow-up of 454 days in the 10 patients who were alive with available data after day 30. Larger prospective studies with the collection of longer-term outcomes are needed to assess our results supporting the safety and effectiveness of cyanoacrylate-lipiodol STAE for rHCC. Randomized trials comparing this mixture to other embolic agents should be performed.

Canine ex vivo tarsal arthrodesis: fixation by using a new bone tissue glue

Introduction

Arthrodesis, performed as a salvage surgical procedure to treat intractable joint conditions in dogs and cats, is associated with a high incidence of complications intra and postoperative, proving the need for improved and new techniques in arthrodesis surgery. Adding a new resorbable bone glue to the arthrodesis could potentially add fixation strength and lower complications. The objectives of this experimental ex vivo biomechanical study were therefore to develop a biomechanical test model of partial tarsal arthrodesis and to determine whether the new resorbable bone glue (phosphoserine modified cement) produced measurable fixation strength in canine calcaneoquartal arthrodesis, without orthopedic implants.

Methods

Four biomechanical test models with a total of 35 canine tarsal joints were used. Soft tissues were dissected to 4 different test models with variable contributions from soft tissues. The calcaneoquartal joint was prepared as in vivo arthrodesis and the glue was applied to joint surfaces as a liquid/putty (0.4 cc). After curing for 24 h, a shear force was applied to the joint (1 mm per minute) and the failure strength was recorded.

Results

Calcaneoquartal joints, where all soft tissues had been completely resected and fixated with glue (1-1.5 cm2 joint surface), withstood 2-5 mm of displacement and an average of 100 ± 58 N/cm2 of shear force (Model 1). Similar adhesive fixation strengths were obtained in Model 2 and 3 with increasing contributions from soft tissues (80 ± 44 and 63 ± 23 N/cm2, p = 0.39, ANOVA).

Conclusion

The developed biomechanical model was sensitive enough to measure differences in fixation strengths between different glue formulations. The average fixation strength (60-100 N/cm2) should be strong enough to support short-term load bearing in medium sized canines (20 kg). The developed cadaver biomechanical test model is of potential use for other arthrodesis studies. The new resorbable glue can potentially contribute to stability at arthrodesis surgery, acting as a complement to today's standard fixation, metal implants.

Characterization of Leptoglossus occidentalis Eggs and Egg Glue

The western conifer seed bug (Leptoglossus occidentalis Heidemann, 1910, Heteroptera: Coreidae) has a significant economic impact due to the reduction in the quality and viability of conifer seed crops; it can feed on up to 40 different species of conifers, showing a clear predilection for Pinus pinea L. in Europe. Its incidence is especially relevant for the pine nut-producing industry, given that the action of this pest insect can reduce the production of pine nuts by up to 25%. As part of ongoing efforts aimed at the design of control strategies for this insect, this work focuses on the characterization (by scanning electron microscopy-energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectroscopy, GC-MS) of the compounds released by these insects during oviposition, with emphasis on the adhesive secretion that holds L. occidentalis eggs together. Elemental analysis pointed to the presence of significant amounts of compounds with high nitrogen content. Functional groups identified by infrared spectroscopy were compatible with the presence of chitin, scleroproteins, LNSP-like and gelatin proteins, shellac wax analogs, and policosanol. Regarding the chemical species identified by GC-MS, eggs and glue hydromethanolic extracts shared constituents such as butyl citrate, dibutyl itaconate, tributyl aconitate, oleic acid, oleamide, erucamide, and palmitic acid, while eggs also showed stearic and linoleic acid-related compounds. Knowledge of this composition may allow advances in new strategies to address the problem caused by L. occidentalis.

Breast Pseudoaneurysm in a Woman after Core Biopsy: Intravascular Glue Embolization

Core needle biopsy of breast masses is a common procedure for tissue diagnosis of breast lesions. The incidence of complications is low, with pseudoaneurysm (PA) after core biopsy has been described in the literature, and the subsequent need for surgical management. Ultrasonography is the most common modality used for not only diagnosis but also treatment of a PA. Color Doppler images show a heterogeneous echoic lesion with whirling flow inside of the lesion. We describe a patient whose breast PA that developed after core needle biopsy was successfully treated with sonographically-guided intravascular glue embolization.

Evaluation of Incisional Wound Healing in Dogs after Closure with Staples or Tissue Glue and Comparison to Intradermal Suture Pattern

The study aimed to monitor the healing process in the canine skin following surgical incision and closure using staples or tissue glue and to compare them with the intradermal suture pattern. Surgically created skin incisions in 10 dogs were apposed with staples, tissue glue (n-butyl cyanoacrylate) and continuous intradermal pattern. The cosmetic appearance of the wounds was blindly evaluated on days 7, 14 and 28 and once a month until the end of the experiment, i.e., one year after the incision. Ultrasonographic and clinical evaluation was performed on days 0-10, 12, 14, 16, 18, 21, 24 and 28, once a week until the end of the 3rd month and once a month until the end of the experiment. Histopathological evaluation was performed on days 7, 14, 28, 180 and 365. The median time required for the performance of each technique differed significantly between techniques; stapling lasted 21 s, glue 2 min 16 s and intradermal 15 min 37 s. Cosmetic appearance with glue was statistically worse than staples and intradermal. The clinical appearance of intradermal was significantly better than glue and staples. No significant differences were found at histological evaluation; however, glue had the worst score throughout the experiment. The overall evaluation of the techniques showed that glue had the worst score compared to intradermal and staples, with the difference being statistically significant in the first postoperative week. Intradermal suture pattern is much better than glue application for skin closure in dogs, whilst is not significantly better than staples. Staples should be preferred when time is an important factor.

Emergency Departments: A 10-Year Overview

Slime's increasing popularity has caused children to be more frequently exposed to glue. There is no comprehensive literature describing pediatric glue-related injuries. This study's purpose is to characterize pediatric glue-related injuries presented to U.S. emergency departments (EDs). We queried the National Electronic Injury Surveillance System for pediatric glue-related injuries from 2009 to 2018. Data were abstracted from discrete and case narrative data. Odds ratios were calculated to determine age-related differences in injuries. An estimated 18,126 pediatric patients were treated in U.S. EDs for glue-related injuries. Injury incidence increased over time. The most frequently injured body part was the eye, and the most common diagnosis was foreign body without documented sequelae. The most common injury mechanism was unintentional splash/squirt/explosion. Younger children were more likely to accidentally ingest glue; older children were more likely to sustain burns. Preventive efforts should focus on personal protective equipment, proper storage/labeling, and supervision of use.

Convergent Evolution of Adhesive Properties in Leaf Insect Eggs and Plant Seeds: Cross-Kingdom Bioinspiration

Plants and animals are often used as a source for inspiration in biomimetic engineering. However, stronger engagement of biologists is often required in the field of biomimetics. The actual strength of using biological systems as a source of inspiration for human problem solving does not lie in a perfect copy of a single system but in the extraction of core principles from similarly functioning systems that have convergently solved the same problem in their evolution. Adhesive systems are an example of such convergent traits that independently evolved in different organisms. We herein compare two analogous adhesive systems, one from plants seeds and one from insect eggs, to test their properties and functional principles for differences and similarities in order to evaluate the input that can be potentially used for biomimetics. Although strikingly similar, the eggs of the leaf insect Phyllium philippinicum and the seeds of the ivy gourd Coccinia grandis make use of different surface structures for the generation of adhesion. Both employ a water-soluble glue that is spread on the surface via reinforcing fibrous surface structures, but the morphology of these structures is different. In addition to microscopic analysis of the two adhesive systems, we mechanically measured the actual adhesion generated by both systems to quantitatively compare their functional differences on various standardized substrates. We found that seeds can generate much stronger adhesion in some cases but overall provided less reliable adherence in comparison to eggs. Furthermore, eggs performed better regarding repetitive attachment. The similarities of these systems, and their differences resulting from their different purposes and different structural/chemical features, can be informative for engineers working on technical adhesive systems.

The Involvement of Cell-Type-Specific Glycans in Hydra Temporary Adhesion Revealed by a Lectin Screen

Hydra is a freshwater solitary polyp, capable of temporary adhesion to underwater surfaces. The reversible attachment is based on an adhesive material that is secreted from its basal disc cells and left behind on the substrate as a footprint. Despite Hydra constituting a standard model system in stem cell biology and tissue regeneration, few studies have addressed its bioadhesion. This project aimed to characterize the glycan composition of the Hydra adhesive, using a set of 23 commercially available lectins to label Hydra cells and footprints. The results indicated the presence of N-acetylglucosamine, N-acetylgalactosamine, fucose, and mannose in the adhesive material. The labeling revealed a meshwork-like substructure in the footprints, implying that the adhesive is mainly formed by fibers. Furthermore, lectins might serve as a marker for Hydra cells and structures, e.g., many labeled as glycan-rich nematocytes. Additionally, some unexpected patterns were uncovered, such as structures associated with radial muscle fibers and endodermal gland cells in the hypostome of developing buds.

Drosophila Glue: A Promising Model for Bioadhesion

The glue produced by Drosophila larvae to attach themselves to a substrate for several days and resist predation until the end of metamorphosis represents an attractive model to develop new adhesives for dry environments. The adhesive properties of this interesting material have been investigated recently, and it was found that it binds as well as strongly adhesive commercial tapes to various types of substrates. This glue hardens rapidly after excretion and is made of several proteins. In D. melanogaster, eight glue proteins have been identified: four are long glycosylated mucoproteins containing repeats rich in prolines, serines and threonines, and four others are shorter proteins rich in cysteines. This protein mix is produced by the salivary glands through a complex packaging process that is starting to be elucidated. Drosophila species have adapted to stick to various substrates in diverse environmental conditions and glue genes appear to evolve rapidly in terms of gene number, number of repeats and sequence of the repeat motifs. Interestingly, besides its adhesive properties, the glue may also have antimicrobial activities. We discuss future perspectives and avenues of research for the development of new bioadhesives mimicking Drosophila fly glue.

Molecular Changes in Spider Viscid Glue As a Function of Relative Humidity Revealed Using Infrared Spectroscopy

Spider aggregate glue can absorb moisture from the atmosphere to reduce its viscosity and become tacky. The viscosity at which glue adhesion is maximized is remarkably similar across spider species, even though that viscosity is achieved at very different relative humidity (RH) values matching their diverse habitats. However, the molecular changes in the protein structure and the bonding state of water (both referred to here as molecular structure) with respect to the changes in RH are not known. We use attenuated total reflectance-infrared (ATR-IR) spectroscopy to probe the changes in the molecular structure of glue as a function of RH for three spider species from different habitats. We find that the glue retains bound water at lower RH and absorbs liquid-like water at higher RH. The absorption of liquid-like water at high RH plasticizes the glue and explains the decrease in glue viscosity. The changes to protein conformations as a function RH are either subtle or not detectable by IR spectroscopy. Importantly, the molecular changes are reversible over multiple cycles of RH change. Further, separation of glue constituents results in a different humidity response as compared to pristine glue, supporting the standing hypothesis that the glue constituents have a synergistic association that makes spider glue a functional adhesive. The results presented in this study provide further insights into the mechanism of the humidity-responsive adhesion of spider glue.

Augmentation of rotator cuff repair with gelatin-resorcin-formalin glue: a biomechanical study

INTRODUCTION

Rotator cuff tendons are typically reattached to the proximal humerus using transosseous sutures or suture anchors. Their primary mode of failure is at the tendon-bone interface.

METHODS

We investigated the addition of an adhesive, gelatin-resorcin-formalin (GRF) glue, to a single-row rotator cuff repair (RCR) on ex vivo sheep models. We hypothesised the addition of GRF glue would increase the repair construct strength. The study consisted of three groups of six sheep infraspinatus tendons with an inverted-mattress stitch, tension-band configuration. Group 1 was the control group where no glue was applied. Group 2 involved applying 2 × 2 cm of GRF glue to the infraspinatus footprint and a 2-min curing time. Group 3 allowed for a 15-min cure time.

RESULTS

Failure occurred at the tendon-bone-suture interface in 6/6 of the control group, and 4/6 from groups 2 and 3. Failure occurred via the suture pulling out of the anchor in 2/6 of groups 2 and 3. No significant differences were noted between all three groups in ultimate failure load, repair stiffness or total energy to failure (p > 0.05).

DISCUSSION

The addition of GRF glue to the tendon-bone-suture interface did not enhance RCR strength in an ovine model.

Fibrin Sealants: Challenges and Solutions

Intraoperative bleeding and postoperative bleeding are major surgical complications. Tissue sealants, hemostats, and adhesives provide the armamentarium for establishing hemostatic balance, including the tissue sealant fibrin. Fibrin sealants combine advantages including instantaneous effect, biocompatibility, and biodegradability. However, several challenges remain. This review summarizes current fibrin product generations and highlights new trends and potential strategies for future improvement.

Glue embolization of a bleeding lingual artery pseudoaneurysm related to tongue surgery

Postoperative lingual artery pseudoaneurysm associated with hemorrhage is a rare entity mainly found after tonsillectomy or laryngectomy. In this report, a symptomatic, lingual artery pseudoaneurysm after repeated base of tongue surgery was identified on computed tomography and successfully managed with catheter-directed glue-embolization.

Hitch suture assisted tuck in Tenon's Patch Graft for management of Corneal Perforations

PURPOSE

To describe a novel modification of tuck-in Tenon's patch graft (TPG) using temporary horizontal mattress sutures and fibrin glue to hitch the graft in the management of corneal perforations.

DESIGN

Ambispective interventional case series.

METHODS

Modified technique of autologous TPG was used to seal corneal perforations measuring 3-5 mm, using horizontal mattress sutures to hitch the graft in a lamellar pocket, followed by application of fibrin glue. The horizontal mattress sutures were removed after the reformation of the anterior chamber. The primary outcome measure was a well formed anterior chamber in the post-operative period and the secondary outcome was epithelization time.

RESULTS

The surgery was performed in 22 eyes. The mean age was 43.86 ± 16.02 (26-66) years, with 14 males and eight females. The etiologies of corneal perforation included dry eye (n = 10), neurotrophic keratitis (n = 6), trauma (n = 2), chemical injury (n = 2) and exposure (n = 2). The mean size of the perforation with the thinned-out area was 4.3 mm (range 3-5 mm). The mean duration of epithelialization was 14.31 ± 2.63 days (7-21 days). No intraoperative complications were observed. All eyes had a well-formed anterior chamber in the immediate postoperative period. Postoperatively, two eyes had graft pseudoectasia due to a thick graft and supra tenon haemorrhage each; one eye each had graft thinning with the formation of pseudopterygium and graft melting.

CONCLUSION

Tenon's patch graft, along with the use of temporary horizontal mattress sutures and fibrin glue, is an effective modification of the technique for managing corneal perforations measuring 3-5 mm.

Images of the month 1: Histoacryl glue embolisation to the right ventricle following treatment for gastric varices

A 46-year-old woman presented with decompensated liver disease. Upper gastrointestinal endoscopy demonstrated a gastric fundal varix with stigmata of recent bleeding. She was treated with Histoacryl glue and lipiodol injection. As a part of a clinical trial, a transthoracic echocardiography was performed. This showed an echogenic mass in the right ventricle. The mass was initially assumed to be thrombus, but as the clinical story did not fit with this, she had further investigations. Computed tomography found the mass to be very radio-opaque with embolisation into the right lung. This is a rare appearance of glue embolisation, a recognised complication of treatment with Histoacryl glue.

Allergic contact dermatitis caused by 2-hydroxyethyl methacrylate and ethyl cyanoacrylate contained in cosmetic glues among hairdressers and beauticians who perform nail treatments and eyelash extension as well as hair extension applications: a systematic review

Current cosmetic regulations primarily focus on protecting consumers, not the professional user who is subjected to a partly different, and certainly more intense exposure to hazardous substances. Against this background, the present systematic review aims to compile and appraise evidence regarding skin toxicity of 2-hydroxyethyl methacrylate (HEMA; CAS no. 212-782-2) and ethyl cyanoacrylate (ECA; CAS no. 7085-85-0) contained in cosmetic glues used among hairdressers and beauticians who perform nail treatments and eyelash extension as well as hair extension applications. This systematic review followed the PRISMA 2020 recommendations for reporting systematic reviews and meta-analysis. In total, 6 publications from 6 countries were eligible for this systematic review. Meta-analysis revealed that hairdressers and beauticians have a 9-fold increased risk of developing contact allergy to HEMA compared to controls who are not hairdressers and beauticians. Results for ECA are lacking. The present systematic review clearly shows that - regarding contact allergy to acrylates - it is not appropriate to apply risk assessment for consumers to hairdressers and beauticians who occupationally handle cosmetic glues. The regulations in existence do not adequately address occupational risks for hairdressers and beauticians connected with the use of acrylate-containing cosmetic substances and need reconsideration. This article is protected by copyright. All rights reserved.

Bleeding Stomal Varices and Their Interventional Management- A Series of Three Cases

Although stomal and parastomal varices are uncommon causes of variceal bleeding, the mortality rate might be as high as 40%. Timely intervention is essential for the management of these ectopic bleeding varices. Due to the rarity of such varices, no standard treatment guideline is available. We present three cases of bleeding stomal varices managed with an endovascular approach, one through percutaneous transhepatic and the other two through transjugular intrahepatic portosystemic shunt approach.

(Un)expected Similarity of the Temporary Adhesive Systems of Marine, Brackish, and Freshwater Flatworms

Many free-living flatworms have evolved a temporary adhesion system, which allows them to quickly attach to and release from diverse substrates. In the marine Macrostomum lignano, the morphology of the adhesive system and the adhesion-related proteins have been characterised. However, little is known about how temporary adhesion is performed in other aquatic environments. Here, we performed a 3D reconstruction of the M. lignano adhesive organ and compared it to the morphology of five selected Macrostomum, representing two marine, one brackish, and two freshwater species. We compared the protein domains of the two adhesive proteins, as well as an anchor cell-specific intermediate filament. We analysed the gene expression of these proteins by in situ hybridisation and performed functional knockdowns with RNA interference. Remarkably, there are almost no differences in terms of morphology, protein regions, and gene expression based on marine, brackish, and freshwater habitats. This implies that glue components produced by macrostomids are conserved among species, and this set of two-component glue functions from low to high salinity. These findings could contribute to the development of novel reversible biomimetic glues that work in all wet environments and could have applications in drug delivery systems, tissue adhesives, or wound dressings.

Bioinspired Underwater Adhesives

Underwater adhesives are in high demand in both commercial and industrial sectors. Compared with adhesives used in dry (air) environments, adhesives used for wet or submerged surfaces in aqueous environments have specific challenges in development and performance. In this review, focus is on adhesives demonstrating macroscopic adhesion to wet/underwater substrates. The current strategies are first introduced for different types of underwater adhesives, and then an overview is provided of the development and performance of underwater adhesives based on different mechanisms and strategies. Finally, the possible research directions and prospects of underwater adhesives are discussed.

Relevant Biological Effects of Varicocele Embolization with N-Butyl Cyanoacrylate Glue on Semen Parameters in Infertile Men

Surgical treatment or varicocele embolization (VE) with sclerosing or mechanical embolic agents have been shown to improve the semen parameters of infertile men. The aim of this study was to evaluate the impact of VE using N-butyl cyanoacrylate (NBCA) glue on semen parameters in infertile men. From January 2014 to June 2018, infertile adult patients with stage 3 varicocele and an initial semen analysis showing at least one abnormal semen parameter, and who were successfully embolized with NBCA Glubran^®2 glue, were retrospectively recruited. The availability of a second semen analysis after VE was mandatory for patient inclusion. The primary endpoint was the change in total sperm number (TSN) after VE. The other parameters of interest were progressive and total sperm motilities (Smot) at 1 h (H1), sperm vitality (SV) and morphology (SMor). One hundred and two patients were included. Eight patients presented null TSN before and after VE. Among the remaining 94 patients, a significant improvement in the median TSN after VE was shown (31.79 × 10⁶/ejaculate [IQR: 11.10-127.40 × 10⁶/ejaculate] versus 62.24 × 10⁶/ejaculate [IQR: 17.90-201.60 × 10⁶/ejaculate], p = 0.0295). Significant improvement in TSN was found for the 60 oligo- or azoospermic patients (p = 0.0007), whereas no significant change was found for the 42 patients with normal initial TSN (p = 0.49). Other parameters, such as progressive and total SMot, SV and SMor, also significantly improved after VE (p = 0.0003, 0.0013, 0.0356 and 0.007, respectively). The use of NBCA glue as an embolic agent for VE in infertile men with stage 3 varicocele significantly improves the semen parameters.

Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications

Endovascular embolization agents are particles and fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude a target vessel, either temporarily or permanently. Vascular embolization agents are available as solids, liquids, and suspensions. Although liquid adhesives (glues) have been used as embolic agents for decades, experience with them for peripheral applications is generally limited. Cyanoacrylates are the main liquid adhesives used for endovascular interventions and have a major role in managing vascular abnormalities, bleeding, and many vascular diseases. They can only be injected as a mixture with ethiodized oil, which provides radiopacity and modulates the polymerization rate. This review describes the characteristics, properties, mechanisms of action, modalities of use, and indications of the cyanoacrylate-Lipiodol® combination for peripheral embolization.

Selective Arterial Embolization of Renal Angiomyolipomas with a N-Butyl Cyanoacrylate-Lipiodol Mixture: Efficacy, Safety, Short- and Mid-Term Outcomes

Selective arterial embolization (SAE) for renal angiomyolipoma (rAML) is effective to treat or prevent bleeding. We report our experience using a cyanoacrylate–Lipiodol mixture. We performed a single-center retrospective review of all rAMLs embolized with cyanoacrylate glue between July 2014 and June 2020. Demographics, tuberous sclerosis complex (TSC) status, clinical presentation, angiography features, and follow-up data were recorded. Pre- and post-procedure rAML sizes and volumes were estimated from computed tomography (CT) or magnetic resonance imaging (MRI) studies. Kidney function was assessed before and after the procedure. We identified 24 patients (22 females and 2 males, mean age 51 years) treated for 27 AMLs, either prophylactically (n = 20) or as an emergency (n = 4). Technical success was achieved for 25/27 AMLs; two patients, each with a single AML, required nephrectomy and repeated embolization, respectively. Major complications occurred in three patients and minor complications such as postembolization syndrome in 15 patients. AML volume reduction after embolization was 55.1% after a mean follow-up of 15 months (range, 1–72 months). Factors associated with greater volume reduction were a smaller percentage of fat (p = 0.001), larger initial rAML volume (p = 0.014), and longer follow-up (p = 0.0001). The mean creatinine level did not change after SAE. Embolization of rAMLs with a mixture of cyanoacrylate and Lipiodol is feasible, safe, and effective in significantly decreasing tumor volume.

Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles

Background

A lot of options have been tried for bridging the two ends of the injured nerves. Researchers have used decellularized nerve grafts, artificial materials and even nerve growth factors to augment functional recovery. These materials are either costly or inaccessible in developing world.

Objective

The study aimed to evaluate the efficacy of the silicone conduit in a rat sciatic nerve injury model.

Materials and Methods

24 healthy Sprague-Dawley (SD) rats (250-300 grams; 8-10 weeks) were used and right sciatic nerve was exposed; transected and re-anastomosed by two different methods in 16 rats. In control group, n = 8 (Group I) the sciatic nerve was untouched; Group II (reverse nerve anastomosis, n = 8): 1-centimeter of nerve was cut and re-anastomosed by using 10-0 monofilament suture; Group III (silicone conduit, n = 8) 1-centimeter nerve segment was cut, replaced by silicone conduit and supplemented by fibrin glue]. Evaluation of nerve recovery was done functionally (pain threshold and sciatic functional index) over 3 months and histologically and electron microscopically.

Results

Functional results showed a trend of clinical improvement in Group III and II but recovery was poor and never reached up to normal. Histopathological and electron microscopic results showed an incomplete axonal regeneration in Groups II and III. Psychological analyses showed that no outwards signs of stress were present and none of the rats showed paw biting and teeth chattering.

Conclusion

The silicone conduit graft may be an economical and effective alternative to presently available interposition grafts, however for short segments only.

A Biomimetic Glue Protein Modulates Hepatic Gene Expression

Glue protein as secretion from fruit fly larva plays a significant role in metamorphosis as cementing material for pupation sites. However, the biochemical composition of this macromolecule remains obscure. This study takes the advantage of high-resolution proteomic analysis to unveil the protein compositions. A glue protein group is identified as chitin-binding motifs by bioinformatic analysis. Computational modeling analysis of representative proteins illustrates the binding site between protein and chitin. A biosynthetic approach is used to fabricate a glue protein by a modified Escherichia coli recombinant system. The as-biosynthesized biomimetic glue protein is applied as an extracellular matrix to investigate its biocompatibility and functionality. It is found that the purified recombinant protein shows enhanced performance to cellular viability. This finding provides a potential biomacromolecule candidate as an extracellular matrix for cell culture.

The use of decorative braces in Jeddah, Saudi Arabia

OBJECTIVE

To assess the practice of using orthodontic brackets as tooth decorations among dental offices and patients in Jeddah, Saudi Arabia.

MATERIALS AND METHODS

The study was a cross-sectional survey using 2 questionnaires. The first included 14 doctor questions where 300 dental offices in Jeddah, Saudi Arabia were contacted by phone. The second questionnaire included 22 patient questions where 50 patients who currently have or have had decorative braces answered the questions online.

RESULTS

Out of 250 dental offices that responded, 91 offices (36.4%) answered "yes" to offering decorative braces. Most dentists use metal brackets (96.3%) on both the upper and lower arches (98.8%) and ligate a wire (83.8%) using colored elastomeric ligatures. Out of 50 patients who answered the patient questions, 28 patients (56%) were females and the mean age was 19.84 years (±2.32). 37 (74%) patients reported that their decorative braces were not placed by dentists and mostly by over the counter glue. Finally, 62% reported they were not satisfied, and 84% said they would not recommend getting decorative braces to their family and friends.

CONCLUSION

Our results indicate that the use of decorative braces is prevalent, and most are not being placed by dentist. As healthcare providers, we are obliged to educate the public of potential harm that can result when decorative braces are used, to hopefully limit the spread of this unfortunate practice.

Comparison of Cost and Efficacy of Trufill® vs Histoacryl® n-Butyl Cyanoacrylate for Translumbar Type 2 Endoleak Embolization

PURPOSE

The study aimed to compare the cost and efficacy of translumbar approach type 2 endoleak repairs using either Trufill® or Histoacryl® n-BCA liquid embolic.

METHOD AND MATERIALS

This was a retrospective review of patients who had translumbar approach type 2 endoleak repairs using either Trufill® or Histoacryl®. Patients were included if they underwent a technically successful type 2 endoleak repair via a translumbar approach with Trufill® or Histoacryl® n-BCA. A multivariable analysis was performed with the primary clinical outcome of percent change in aneurysm diameter per month compared. Procedure cost was calculated based on typical materials used.

RESULTS

20 Trufill® and 14 Histoacryl® patients were included. The mean procedure cost was higher for Trufill® ($5,757.30 vs. $1,586.09, p ≤ 0.001). There was no significant difference between Trufill® or Histoacryl® patients for age at first embolization, gender, total number of embolizations, number of feeding branches, aneurysm sac size prior to embolization, or residual endoleak at first follow-up. Trufill® patients had more coils used (12.0 vs. 4.3, p = 0.0007), less glue used (0.9 vs. 2.1 mL, p < 0.001), longer follow-up duration (33.5 vs. 13.2 months, p = 0.002), more follow-up CT angiograms (CTA) (3.7 vs. 1.9, p = 0.01), and larger excluded aneurysm sac size at most recent CTA (7.1 cm vs. 5.9 cm, p = 0.04). Percent change in sac diameter per month was not significantly different between Trufill® and Histoacryl® (0.21% vs. -0.25%/month, p = 0.06, respectively). There were no complications.

CONCLUSION

Use of Histoacryl® over Trufill® n-BCA resulted in significantly less procedural cost while maintaining safety and efficacy.

A New Approach Based on Glued Multi-Ultra High Molecular Weight Polyethylene Forms to Fabricate Bone Replacement Products

Three types of glue based on thiol-ene reaction, polyvinyl alcohol (PVA)/cellulose, and phenol formaldehyde were prepared and applied on modified ultra-high molecular weight polyethylene (UHMWPE) samples grafted by cellulose. In comparison with unmodified UHMWPE samples, T-peel tests on the modified and grafted UHMWPE films showed an increase in the peel strength values for the glues based on thiol-ene reaction, PVA/cellulose, and phenol formaldehyde by 40, 29, and 41 times, respectively. The maximum peel strength value of 0.62 Kg/cm was obtained for the glue based on phenol formaldehyde. Mechanical tests for the cylindrical multi-UHMWPE forms samples, made of porous UHMWPE as a trabecular layer and an armored layer (cortical layer) that consists of bulk and UHMWPE films, indicated an improvement in the mechanical properties of these samples for all glue types, as a result of the UHMWPE films existence and the increase in the number of their layers. The maximum compressive yield strength and compressive modulus values for the armored layer (bulk and six layers of the UHMWPE films using the glue based on thiol-ene reaction) were 44.1 MPa (an increase of 17%) and 1130 MPa (an increase of 36%), respectively, in comparison with one armored layer of bulk UHMWPE. A hemocompatibility test carried out on these glues clarified that the modified UHMWPE grafted by cellulose with glues based on PVA/cellulose and thiol-ene reaction were classified as biocompatible materials. These multi-UHMWPE forms composites can be considered a promising development for joint reconstruction.

The effect of bovine serum albumin-glutaraldehyde and polyethylene glycol polymer on neointimal hyperplasia in rabbit carotid artery anastomosis

OBJECTIVE

Since the systemic drugs have been used to reduce the hyperplasic response in the tunica intima, the periadventitial local drug applications to the vascular wall have gained more popularity. In this study, we investigated the effect of bovine serum albumin-glutaraldehyde and polyethylene glycol polymer on neointimal hyperplasia in rabbit carotid artery anastomosis to explore the effects of these two different agents.

METHODS

21 New Zealand male rabbits were randomly divided into three groups. The carotid artery transection and anastomosis was performed onthe control group. The bovine serum albumin-glutaraldehyde and the polyethylene glycol polymer were applied locally on the other two groups seperatley after transection and anastomosis of the carotid arteries. At the end of 28-day follow-up, the histological and the immunohistochemical results related to neointimal hyperplasia were compared.

RESULTS

The glue residues were detected in the BSA-glutaraldehyde group, but in the PEG polymer group there was no glue residue. The intima thickness and the intima/media thickness ratio in the control group was significantly higher (p<0.05) than the other groups. These values did not differ significantly between the BSA-glutaraldehyde group and the PEG polymer group (p>0.05). The lumen diameter and the area in the control group were significantly higher (p < 0.05) than the BSA-glutaraldehyde group. These values between the control group and the PEG polymer group did not differ significantly (p>0.05). aSMA-positive staining score in the Control group was found to be significantly lower (p < 0.05) than the BSA-glutaraldehyde and PEG polymer group and the VEGF-positive staining score in the control group was found to be significantly higher (p < 0.05) than the BSA-glutaraldehyde and the PEG polymer group.

CONCLUSIONS

Although the both agents have positive results on neointimal hyperplasia, it would be favorable to use polyethylene glycol polymer, since it does not seem to affect the lumen area and the lumen diameter of the vessel.

Adhesion Performance in the Eggs of the Philippine Leaf Insect Phyllium Philippinicum (Phasmatodea: Phylliidae)

Leaf insects (Phasmatodea: Phylliidae) exhibit perfect crypsis imitating leaves. Although the special appearance of the eggs of the species Phyllium philippinicum, which imitate plant seeds, has received attention in different taxonomic studies, the attachment capability of the eggs remains rather anecdotical. We herein elucidate the specialized attachment mechanism of the eggs of this species and provide the first experimental approach to systematically characterize the functional properties of their adhesion by using different microscopy techniques and attachment force measurements on substrates with differing degrees of roughness and surface chemistry, as well as repetitive attachment/detachment cycles while under the influence of water contact. We found that a combination of folded exochorionic structures (pinnae) and a film of adhesive secretion contribute to attachment, which both respond to water. Adhesion is initiated by the glue, which becomes fluid through hydration, enabling adaption to the surface profile. Hierarchically structured pinnae support the spreading of the glue and reinforcement of the film. This combination aids the egg’s surface in adapting to the surface roughness, yet the attachment strength is additionally influenced by the egg’s surface chemistry, favoring hydrophilic substrates. Repetitive detachment and water-mediated adhesion can optimize the location of the egg to ensure suitable environmental conditions for embryonic development. Furthermore, this repeatable and water-controlled adhesion mechanism can stimulate further research for biomimeticists, ecologists and conservationalists.

Endovascular Embolization of a Previously Treated Renal Arteriovenous Malformation Presenting With Gross Hematuria

Renal arteriovenous shunts are direct communications between the supplying artery and draining vein without the presence of an intervening capillary bed. They can be traumatic or nontraumatic. Coils can be used for embolization of feeding arteries; however, they do not treat the nidus directly. We report a case in which proximal coil placement in feeding arteries led to recanalization of the renal AV shunt through collaterals, resulting in recurrent hematuria. The case was subsequently managed by embolizing the nidus by N-butyl 2-cyanoacrylate glue.

Corneal Sealants in Clinical Use: A Systematic Review

AIM

To review the use of clinical corneal sealants for the closure of full thickness corneal wounds.

METHODS

A systematic review was conducted across CENTRAL, Medline, PubMed, Embase, Scopus, mRCT and ICTRP for the keywords of 'cornea', 'full-thickness wound', 'sealant' and their synonyms. Only evidence level 2 of higher as graded by Oxford Centre of Evidence-based Medicine were included for this review.

RESULTS

Seven studies were included; three randomized controlled trials investigated ReSure® sealant, 2 OcuSeal®, 1 human fibrin glue vs cyanoacrylate and 1 human fibrin glue as an adjunct to sutures vs sutures alone in penetrating keratoplasty. ReSure® was superior to suture for sealing leaking corneal incisions after cataract surgery despite provocation. ReSure® sealant has not been tested on complex full thickness corneal wounds, perforated ulcers or penetrating keratoplasty. OcuSeal® was also able to seal full thickness cornea wound post-cataract surgery to prevent ingress of Trypan blue dye. Human fibrin glue and cyanoacrylate were similarly effective in treating corneal perforations <3 mm of mixed etiologies.

CONCLUSION

There are limited high-level evidence for corneal sealants. The currently available sealants with human data are ReSure®, OcuSeal®, human fibrin glue and cyanoacrylates. While ReSure® and OcuSeal® are effective post-cataract surgery, there are no data for perforations from other etiologies. Post-approval data from ReSure® registry report good tolerability and no apparent safety concerns.

Feasibility and Safety of Sac Embolization Using N-Butyl Cyanoacrylate in Emergency Endovascular Aneurysm Repair for Ruptured Abdominal Aortic Aneurysms or Isolated Iliac Artery Aneurysms

PURPOSE

To evaluate the feasibility and safety of sac embolization with N-butyl cyanoacrylate (NBCA) in emergency endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysm (AAA) and iliac artery aneurysm (IAA) in comparison to EVAR without sac embolization.

MATERIALS AND METHODS

Between February 2012 and December 2019, among 44 consecutive patients with ruptured AAA or IAA, 29 underwent EVAR. Of these, 22 patients (median age 77.5 years; 18 men) had concomitant sac embolization using NBCA; the remaining 7 patients (median age 88 years; 6 men) underwent EVAR without sac embolization and form the control group. The technical success, clinical success (hemodynamic stabilization), procedure-related complications, and mortality were compared between the groups.

RESULTS

All EVAR procedures and embolizations were successful. The clinical success rates in the NBCA and control groups were 95% (21/22) and 71% (5/7), respectively (p=0.14). There was no complication related to the procedure. Type II endoleak occurred in 4 of 21 patients (19%) in the NBCA group vs none of the control patients. One patient (5%) died in the NBCA group vs 3 (43%) in the controls (p=0.034).

CONCLUSION

Sac embolization using NBCA in emergency EVAR appears to be feasible and safe for ruptured AAA and IAA.

Laparoscopic Injection of Tissue Adhesives for Inguinal Hernia Repair in a Rabbit Model: Results of an Experimental Comparative Study with the Standard Laparoscopic Inguinal Hernia Repair

Background: The injection of tissue adhesives has been proposed as an alternative to standard laparoscopic inguinal hernia repair but no evidence is available in the pediatric population. This study aimed to evaluate safety, efficacy, and feasibility of injection of tissue adhesives for inguinal hernia repair in a rabbit model. Materials and Methods: Thirty-six New Zealand White male rabbits underwent laparoscopic inguinal hernia repair. In each animal, the hernia defect was repaired using glue on the right side and purse-string suture on the left side. The animals were divided in 3 groups, each 1 of 12 animals, according to the glue used: Glubran 2^® (cyanoacrylate), Histoacryl^® (cyanoacrylate), and BioGlue^® (bovine serum albumin-based). For each group, 6 animals were sacrificed at 7 days postoperatively, and 6 animals at 90 days postoperatively. Histopathological exam of testis and spermatic bundle was performed. Results: The hernia defect was successfully closed on both sides in all cases. The injection of glue was faster than suture repair (P = .001). Postoperative complications (epiploon-parietal adhesions, spermatic vessel ectasia, and hydrocele) rate was significantly higher on the right side compared to the left side at both short- and long-term follow-up (P = .001). Furthermore, a lower maturity of testicles treated by adhesive compared with suture was histologically demonstrated at both short- and long-term follow-up (P = .001). Conclusions: The present experimental study confirmed the feasibility and efficacy of inguinal hernia repair by injection of tissue adhesive. However, several critical issues emerged about the safety of this technique. The use of glue was associated with higher incidence of postoperative complications and significant decrease of testicular maturity compared with standard suture repair. Based upon these preliminary results, repair using suture remains the standard of care for inguinal hernia in children. Further experimental studies are needed to assess the safety of injection of tissue adhesives for pediatric inguinal hernia repair.

Prevalence of glue-sniffing among street children

Aim

The aim was to determine the prevalence of glue-sniffing among street children.

Design

A descriptive cross-sectional study design was adopted.

Background

Children are the source of hope and could be the major ailments for the development of society, nation and the world but there are large numbers of children on the street sniff glue and struggling with multiple disease and uncertain future.

Methods

A study was conducted in 52 street children to determine the prevalence of glue-sniffers and its impact on street children in Butwal, municipality of Nepal. This study was conducted in 52 street children, 5- point Likert scale and interview schedule was performed with the help of structured and semi-structured questionnaire to collect data. Finally, the collected data are analysed by using descriptive statistical methods such as frequency, percentage and mean.

Results

The study findings revealed that a large number of children, that is 40.38% was between the age group of 9-12 years and 92.31% were male. The current prevalence of glue-sniffing among street children is 88.46%. Similarly, 58.7% of respondents had started glue-sniffing 1 year ago. Out of 46 respondents who sniffed glue, 89.13% were unaware of its effect. Nearly, half of the respondents 45.65% had encountered health issues such as headache, chest pain and stomach ache.

Conclusions

They have deprived children and denied not only of their rights as children but also of their normal childhood. Without guidance, education and security, they are heading towards an uncertain future. They can have enough potentiality and talent if they are brought into a better environment and might have real hope for the bright future.

A Prospective Controlled Study on Long-Term Outcomes of Facial Lacerations in Children

Background: Although skin adhesives have been used for decades to treat skin lacerations, uncertainty remains about long-term results, and complications. Methods: In this prospective, controlled, single-blinded, observational cohort study, outcomes were assessed by five plastic surgeons with standardized photographs at 6-12 months using a modified Patient and Observer Scar Assessment Scale (POSAS) and Vancouver Scar Scale (VSS); additionally, the POSAS was performed by the patients/caregivers and the physician; pain, requirement of anesthesia, treatment time, costs, complications, and quality of live (QoL) were assessed. Results: A total of 367 patients were enrolled; 230 were included in the main analysis; 96 wounds were closed using tissue adhesives (group 1); 134 were sutured (group 2). Assessment by the independent observers revealed an improved mean modified overall POSAS score in group 1 in comparison with group 2 [2.1, 95% CI [1.97-2.25] vs. 2.5, 95% CI [2.39-2.63]; p < 0.001, d = 0.58] and mean VSS score [1.2, 95% CI [0.981-1.34] vs. 1.6, 95% CI [1.49-1.79], p < 0.001, d = 0.53]. At the early follow-up, dehiscence rate was 12.5% in group 1 and 3.7% in group 2 (p < 0.001); later on, one dehiscence remained per group. Mild impairment of QoL was found at the early follow-up in both groups, with no impairment remaining later on. Duration of treatment and treatment costs were lower in group 1. Conclusion: Both modalities of wound closure yield favorable esthetic results, and complications are rare. Adhesives are more cost-effective, and its application is less time-consuming; therefore, tissue adhesives offer considerable advantages when used appropriately. Trial Registration: Public trial registration was performed at www.ClinicalTrials.gov (Identifier: NCT03080467).

Current State of Bone Adhesives-Necessities and Hurdles

The vision of gluing two bone fragments with biodegradable and biocompatible adhesives remains highly fascinating and attractive to orthopedic surgeons. Possibly shorter operation times, better stabilization, lower infection rates, and unnecessary removal make this approach very appealing. After 30 years of research in this field, the first adhesive systems are now appearing in scientific reports that may fulfill the comprehensive requirements of bioadhesives for bone. For a successful introduction into clinical application, special requirements of the musculoskeletal system, challenges in the production of a bone adhesive, as well as regulatory hurdles still need to be overcome. In this article, we will give an overview of existing synthetic polymers, biomimetic, and bio-based adhesive approaches, review the regulatory hurdles they face, and discuss perspectives of how bone adhesives could be efficiently introduced into clinical application, including legal regulations.

Bioadhesives in neurosurgery: a review

OBJECTIVE

Neurosurgery presents unique surgical challenges arising from delicate neural structures, limited accessibility, and the risk of CSF leakage that can lead to CNS infections. Sutures and staples may have limited applicability in the complex anatomical constraints of cranial and spinal surgeries, especially in trauma settings when time is of the essence. Surgical bioadhesives are emerging as attractive alternatives because they avoid traumatic application methods, provide a stress-distributed fixation, and provide good cosmesis and outcomes. This article presents the history of the development of surgical bioadhesives, and is also a review of current applications of commercial surgical bioadhesives within neurosurgical procedures and the unmet clinical needs that should be addressed in bioadhesives technologies.

METHODS

A PubMed literature search was performed using the terms "(glue OR bioadhesive OR fibrin OR tisseel OR evicel OR tachosil OR cyanoacrylate OR duraseal OR bioglue) AND (neurosurgery OR spine OR spinal OR dural OR microvascular decompression OR transsphenoidal OR endovascular)." Of 2433 records screened, 168 studies were identified that described the use of bioadhesives in neurosurgical procedures.

RESULTS

The greatest number of studies describing the use of bioadhesives in neurosurgery were identified for endovascular embolization, followed by dural closure and transsphenoidal surgeries. Other common areas of application were for microvascular decompression, skin closure, peripheral nerve repair, and other novel uses. Numerous case reports were also identified describing complications associated with bioadhesive use.

CONCLUSIONS

Despite the paucity of approved indications, surgical bioadhesive use in neurosurgical procedures is prevalent. However, current bioadhesives still each have their own limitations and research is intense in the development of novel solutions.

Elasticity and energy dissipation in the double network hydrogel adhesive of the slug Arion subfuscus

The slug Arion subfuscus produces a mucus-based defensive secretion that is remarkably tough. This glue appears to be a double network hydrogel, gaining its toughness through the synergistic actions of two networks of polymers, a relatively stiff network and a relatively deformable network. The double network mechanism has great potential to guide the development of synthetic adhesives. Mechanical tests were performed to analyse key predictions of the mechanism. Stress relaxation tests and tensile tests support the presence of stable cross-links. Cyclic stress-strain tests demonstrate that the glue dissipates a great deal of energy through the failure of these cross-links as sacrificial bonds. Energy dissipation by failure of sacrificial bonds rather than viscous processes is supported by the minimal effect of the time course of the experiments on the measured properties. These sacrificial bonds appear able to reform within minutes after failure. Finally, the glue's stiffness decreases at pH values below 5.5, whereas magnesium and calcium rapidly dissociate from the glue at all pH values tested. Thus, these ions may not be the primary cross-linkers generating the glue's stiffness. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.

The current knowledge about the therapeutic use of endoscopic sclerotherapy and endoscopic tissue adhesives in variceal bleeding

Introduction: The most recent guidelines vary in their approach to the management of variceal bleeding especially with the use of endoscopic sclerotherapy (ES) and endoscopic tissue adhesive (ETA). This review highlights their clinical use for variceal bleeding from different guidelines perspectives. Areas covered: A comprehensive literature review of three major guidelines including the American Association for the Study of Liver Diseases (AASLD) 2017, United Kingdom (UK) guidelines 2015 and Baveno VI Consensus workshop guidelines in 2015 on the use of ES and ETA in variceal bleeding. Expert opinion: While endoscopic band ligation (EBL) completely replaced endoscopic sclerotherapy (ES) for esophageal varices. There is a valuable use of endoscopic sclerotherapy (ES) and endoscopic tissue adhesive (ETA) especially for patients with gastroesophageal varices (GOV2) and isolated gastric varices (IGV2). The current standard of care heading toward portosystemic shunting with Trans-jugular-Intrahepatic Portosystemic Shunt (TIPS) and balloon retrograde transvenous obliteration (BRTO). However, recent advancement in endoscopic ultrasound (EUS) allowing direct injection of sclerosant and tissue adhesive into the varix bringing promising results in achieving hemostasis and lowering the risk of complications. Also, ES and ETA have great clinical value in achieving hemostasis for isolated (ectopic) varices and stomal varices.

Cyanoacrylate closure for peripheral veins: Consensus document of the Australasian College of Phlebology

Background

Cyanoacrylates are fast-acting adhesives used in procedural medicine including closure of superficial wounds, embolization of truncal vessels pre-operatively, vascular anomalies, visceral false aneurysms, endoleaks, gastrointestinal varices and gastrointestinal bleeding. More recently, catheter-directed cyanoacrylate adhesive closure was introduced as an alternative to endovenous thermal ablation (ETA) to occlude superficial veins of the lower limbs.

Objectives

To formulate policies for the safe and effective delivery of cyanoacrylate adhesive closure procedures in Australasia, based on current experience and evidence.

Methods

A panel of phlebologists including vascular surgeons, interventional radiologists, dermatologists and research scientists systematically reviewed the available data on cyanoacrylate products used in medicine and shared personal experience with the procedure. The reviewed material included bibliographic and biomedical data, material safety data sheets and data requested and received from manufacturers. Results and recommendations: Cyanoacrylate adhesive closure appears to be an effective treatment for saphenous reflux with occlusion rates at 36 months of 90–95%. We recommend a maximum dose of 10 mL of cyanoacrylate per treatment session. Serious complications are rare, but significant. Hypersensitivity to acrylates is reported in 2.4% of the population and is an important absolute contraindication to cyanoacrylate adhesive closure. 1 Post-procedural inflammatory reactions, including hypersensitivity-type phlebitis, occur in 10–20% of patients. 2 In the long term, cyanoacrylate adhesive closure results in foreign-body granuloma formation within 2–12 months of the procedure. We recommend against the use of cyanoacrylate adhesive closure in patients with uncontrolled inflammatory, autoimmune or granulomatous disorders (e.g. sarcoidosis). Caution should be exercised in patients with significant active systemic disease or infection and alternative therapies such as thermal ablation and foam sclerotherapy should be considered.

Conclusions

Cyanoacrylate adhesive closure appears to be an effective endovenous procedure, with short-term closure rates comparable to ETA and therefore greater efficacy than traditional surgery for treating superficial veins of the lower limbs. Ongoing data collection is required to establish the long-term safety.

Granuloma formation following cyanoacrylate glue injection in peripheral veins and arteriovenous malformation

Background

Cyanoacrylate adhesive closure is a technically simple alternative to endothermal ablation of peripheral veins. N-butyl cyanoacrylate is delivered via catheters or by percutaneous injection resulting in occlusion of target veins. The local tissue reaction or the systemic immune response that may follow have not been characterised.

Aim

To characterise the late local tissue reaction to N-butyl cyanoacrylate glue injected in peripheral vessels.

Methods

Biopsies were obtained from two patients. In patient one, distal tributaries of the great saphenous vein were injected with VenaBlock™ glue under ultrasound guidance. Ultrasound-guided incisional biopsies were performed at one week, six weeks and 12 months. In patient two, a peripheral arterio-venous malformation was injected with Venablock™ and biopsy was performed 12 months later. Histological analysis was performed using haematoxylin and eosin and immunofixation with CD-4, CD-31, CD-34, CD-68 and D2-40.

Results

Echogenic material with a strong shadow artefact consistent with the injected N-butyl cyanoacrylate was observed on ultrasound on all follow-up occasions. Biopsies taken at one week showed intravascular glue without histiocytes. Biopsies at six weeks showed isolated foreign body histiocytes coating intravascular fibrillary glue spicules but no granuloma formation. The one-year biopsies showed extravascular changes including fibrosis, lymphoid aggregates and multiple extravascular foreign body cavitated granulomas. Some vessel lumens contained residual spicules of glue but no intravascular granulomas. The extravascular granulomas were deeply located, asymptomatic and not complicated by clinical ulceration. Histologically, there was no evidence of transepidermal elimination.

Conclusion

Extravascular foreign body cavitated granulomas containing spicules of glue with fibrosis and lymphoid aggregates occur as a delayed finding following the use of N-butyl cyanoacrylate.

Glue embolisation of a bleeding pseudoaneurysm related to surgically-assisted rapid palatal expansion

Vascular injuries after orthognathic surgery are rare, and mainly occur in young adults after Le Fort I osteotomies. We report the case of a 14-year-old girl who presented with life-threatening epistaxis one week after a surgically-assisted rapid palatal expansion (SARPE) followed by activation of a transpalatal distractor. Definitive treatment was superselective, catheter-directed, glue-embolisation of a bleeding bilobar pseudoaneurysm, which was located at an end branch of the left sphenopalatine artery.

Endovascular Management of Vein of Galen Aneurysmal Malformations: A Retrospective Analysis over a 15-Year Period

OBJECTIVES

This retrospective study was aimed at assessing our results of endovascular management in vein of Galen aneurysmal malformation (VGAM).

MATERIALS AND METHODS

This is a retrospective study of 26 patients of VGAM who underwent endovascular treatment between 1998 and 2012. All patients underwent trans-arterial embolization. Of 26 patients, 23 were treated using n-butyl cyano acrylate (Glue), while 3 out of 26 patients were treated using the ethylene vinyl alcohol (EVOH) copolymer.

RESULTS

Ages of the treated patients ranged from 1 day to 18 years of age. Of the patients treated, 17 were males and 9 were females. Around 15 of the VGAMs were of the mural variety and 11 were choroidal in nature. A good outcome was seen in 22/26 (85%) of the patients. Complications were seen in total in 7/26 patients (26.92%) of which 3/26 (12%) has a fatal outcome.

CONCLUSION

Endovascular embolization for VGAMs is highly efficacious and has helped create a population of VGAM survivors in this condition, which until only a few decades ago caused high mortality and morbidity.