Short Graft Research Articles

Descemet Membrane Endothelial Keratoplasty Outcomes between Young and Old Graft Recipients

ABSTRACT Purpose: To evaluated Descemet’s membrane endothelial keratoplasty (DMEK) outcomes in young and old graft recipients. Materials and Methods: Data of 164 surgeries with a median age of 76 years (interquartile range 14 years) undergoing DMEK surgery between 2016 and 2018 was reviewed. Complications, graft survival, and visual acuity gain were compared between subjects in the 25th percentile (young recipients; aged 70 years and less, n = 21) and 75th percentile (old recipients; aged 85 years and over, n = 27) over the 2-year follow-up. Results: Young recipients had a lower rate of pre-operative glaucoma (14.3% vs. 51.9%, p = .014) and pseudophakic bullous keratopathy (9.5% vs. 59.3%, p < .001), and a higher rate of Fuchs endothelial dystrophy (57.1% vs. 14.8%, p = .002) and combined cataract extraction at the time of DMEK surgery (52.4% vs. 7.4%, p = .001) when compared to old recipients. Complications (primary graft failure, pupillary block, cystoid macular edema or infectious keratitis) were independent of graft recipient age. Descemet’s membrane detachment requiring re-bubbling was observed more often in young compared to the old recipients (42.9% vs. 14.8%, p = .049). Visual acuity gain between the groups remained comparable up to 1-year, whereas at 2-years old recipients showed significantly declined visual acuity gains compared to the young recipients (0.14 ± 0.68 vs. 0.74 ± 0.49, p = .012). Graft recipients aged over 85 years had a considerably higher graft failure rate over the 24-months (40.7% vs. 4.8%, p = .006) and shorter graft survival time (p = .002; log-rank) when compared to the recipients aged under 70 years. After adjusting for potential confounders such as Fuchs endothelial dystrophy, pseudophakic bullous keratopathy and glaucoma, the recipients aged over 85 remained at higher risk for graft failure (HR = 17.278, 95% CI = 1.787–167.1, p = .014). Conclusions: In aged DMEK recipients, regardless of the low incidence of early postoperative complications, the rate of postoperative graft failure was significantly higher and graft survival shorter than in younger recipients.

Splenic Artery Transposition for Hepatic Artery Reconstruction During Liver Transplantation: Is It the Best Choice for Adequate Arterial Inflow in Extraordinary Conditions?

Obtaining partial allografts and performing arterial reconstruction in living donor liver transplantation (LDLT) is technically demanding. The risk of hepatic artery thrombosis (HAT) remains high in LDLT due to the small caliber of the arteries. The graft and the recipient hepatic artery (HA) cannot be directly anastomosed in certain cases due to narrow diameter or short graft HA.

Green and sustainable method of manufacturing anti-fouling zwitterionic polymers-modified poly(vinyl chloride) ultrafiltration membranes

The nonsolvent induced phase separation (NIPS) method for ultrafiltration (UF) membrane fabrication relies on the extensive use of traditional solvents, thus ranking first in terms of ecological impacts among all the membrane fabrication steps. Methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean), as a green solvent, was utilized in this study to fabricate poly(vinyl chloride) (PVC) UF membranes. Subsequently, in post-treatment process, zwitterionic polymer, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (DMAPS), was grafted onto the membrane surface to enhance its anti-fouling properties using a greener surface-initiated activator regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) reaction. This novel method used low toxicity chemicals, avoiding the environmental hazards of traditional ATRP, and greatly improving the reaction efficiency. We systematically studied the grafting time effect on the resulted membranes using sodium alginate as the foulant, and found that short grafting time (30 min) achieved excellent membrane performance: pure water permeability of 2872 L m−2 h−1 bar−1, flux recovery ratio of 86.4% after 7-hour fouling test, and foulant rejection of 96.0%. This work discusses for the first time the greener procedures with lower environmental impacts in both fabrication and modification processes of PVC UF membranes.

Combined Anterior and Anterolateral Stabilization of the Knee With the Hamstring Tendons

Anterior cruciate ligament reconstruction allows good control of sagittal laxity but insufficient rotary laxity control. Our objective is to describe an original lateral extra-articular tenodesis using gracilis in addition to an intra-articular reconstruction using the semitendinosus in a short 4-strand graft. The principles are as follows: The femoral tunnel for intra-articular and extra-articular reconstruction is unique, the femoral attachment is posterior and proximal to the lateral epicondyle, the graft is under the lateral collateral ligament, and the tibial insertion is isometric from 0° to 60° between the Gerdy tubercle and the fibular head.

Adjustable suspension versus hybrid fixation in hamstring autograft anterior cruciate ligament reconstruction

BackgroundThere has been increased use of adjustable suspensory fixation (ASF) for anterior cruciate ligament reconstruction (ACLR). Potential benefits are the ability to use a shorter graft and to prevent graft displacement and damage. The purpose of this study was to establish the efficacy of this fixation method and assess whether it leads to less tunnel widening, and avoids known complications of screw fixation. MethodsThirty-eight patients who underwent ACLR with ASF on both the femoral and tibial sides met the inclusion criteria and were propensity matched demographically with 38 patients who underwent hybrid fixation with femoral suspensory and tibial screw and sheath. At one-year, KT-1000 knee laxity measurements were recorded and detailed MRI analysis looking at tunnel aperture widening, tunnel appearance, graft integration within the tunnels, and graft healing. ResultsMRI comparison between ASF and hybrid cohorts revealed no significant differences in graft signal or integration, and clinically there were no differences in knee laxity between cohorts (mean 1.5 mm ± 2.0 and 1.5 mm ± 2.3 (n.s.) in the ASF and hybrid fixation respectively). Significantly less aperture tibial tunnel widening (2.2 mm versus 4.4 mm, p < 0.0001) and tibial cysts (2 versus 9, p = 0.047) were observed in the ASF cohort, whilst mean femoral tunnel widening was comparable between both cohorts (ASF 2.8 mm, hybrid 3.2 mm; n.s.). ConclusionsHamstring autografts for ACLR fixed using either ASF or a hybrid fixation technique provided comparable knee stability and MRI graft signal intensity. Tibial ASF demonstrated significantly less tibial aperture widening and tunnel cyst formation when compared to screw and sheath fixation.

Latissimus Dorsi-lumbar Artery Perforator Chimeric Flap with Intra-flap Crossover Anastomosis for Breast Reconstruction.

Latissimus dorsi (LD) flaps are widely used in breast reconstruction for their ease of use and minimal sacrifice of the donor site. Various strategies to increase flap volume have been suggested, but tissue volume is often insufficient for patients with little subcutaneous fat. While lumbar artery perforator (LAP) flaps are advantageous for thin patients because they allow for the addition of a large amount of fat, the vascular pedicle is short and vascular grafts are often required. To address these shortcomings, we propose here a LD-LAP chimeric flap. Specifically, the LD flap and LAP flap are elevated as one piece, and the 6th or 7th intercostal artery perforators and lumbar artery perforators, which are harvested together with the flap, are connected via intra-flap crossover anastomosis. Anastomosis for both intercostal artery perforators and lumbar artery perforators was performed about 1 cm away from the flap. Indocyanine green angiography performed after anastomosis showed improved blood flow to the LAP flap portion of the chimeric flap. The chimeric flap was used in 4 patients, with a mean flap volume of 460 ml (range, 300-690 ml) and mean duration of 439 minutes (393-484 minutes) for reconstruction surgery. During the mean follow-up period of 29.5 months (range, 16-40 months), sufficient tissue volume was obtained and none of the patients developed flap necrosis. Although our method requires vascular anastomosis and may extend operative time, it substantially increases LD flap volume and thus is likely to be an effective auxiliary component to breast reconstruction using LD flaps.

Kidney transplantation outcomes from elderly donors after circulatory death: a comparison with elderly brain-dead donors.

BackgroundThe use of kidneys from elderly controlled donation after circulatory death (cDCD) donors has increased significantly in recent years. Concerns about outcomes achieved with these elderly cDCD kidneys have arisen. We aimed to compare outcomes from elderly cDCD kidney transplant recipients (KTrs) and elderly donation after brain death donors (DBDs) in KTrs.MethodsWe conducted a single-centre retrospective study including 87 cDCD-KTrs (46 from donors ≥65 years of age and 41 from <65 years) and 126 DBD-KTrs from donors ≥65 years of age from 2013 through 2017). Young cDCD-KTrs were used as controls. The median follow-up was 27.1 months for all cDCD-KTrs and 29.7 months for DBD-KTrs ≥65 years of age.ResultsDonors >65 years of age represented more than half of our global cDCD cohort (52.9%). KTs from elderly cDCDs had similar rates of delayed graft function, primary non-function and vascular complications compared with young cDCD-KTrs and elderly DBD-KTrs. Short and medium-term graft survival from elderly cDCD kidneys are excellent and are comparable to those from young cDCD and elderly DBD kidneys (90% young cDCD versus 88% elderly cDCD versus 80% elderly DBD at 36 months, P = 0.962 and 0.180, respectively). Although recipients from cDCDs ≥65 years of age showed lower 3-year patient survival (78% versus 87% in elderly DBD-KTrs; P = 0.01), recipient age was the only determinant of patient survival [hazard ratio 1.10 (95% confidence interval 1.02–1.17); P < 0.01], without any influence of donor characteristics.ConclusionsThe use of kidneys from elderly cDCDs is increasing in Spain. Short- and medium-term graft outcomes are similar when comparing kidneys from elderly cDCDs and DBDs. Recipient age is the only determinant of patient survival. Additional studies are needed to assess long-term outcomes.

Mitigation of Physical Aging with Mixed Matrix Membranes Based on Cross-Linked PIM-1 Fillers and PIM-1.

A low cross-link density (LCD) network-PIM-1, which offers high compatibility with the polymer of intrinsic microporosity PIM-1, is synthesized by a modified PIM-1 polycondensation that combines both a tetrafluoro- and an octafluoro-monomer. To maximize the advantages of utilizing such cross-linked PIM-1 fillers in PIM-1-based mixed matrix membranes (MMMs), a grafting route is used to decorate the LCD-network-PIM-1 (dispersed phase) with PIM-1 chains, to further enhance compatibility with the PIM-1 matrix. Mixed-gas CO2/CH4 (1:1, v/v) separation results over 160 days of membrane aging confirm the success of a relatively short (24 h) grafting reaction in improving the initial CO2 separation performance, as well as hindering the aging of PIM-1/grafted-LCD-network-PIM-1 MMMs. For MMMs based on a 24 h grafting route, all the gas separation data surpass the 2008 Robeson upper bound by a significant margin, and the 160-day aged membranes show only 29% reduction from the initial CO2 permeability, which is substantially less than the equivalent losses of nearly 70% and 48% for PIM-1 and traditionally fabricated MMMs counterparts, respectively. These results demonstrate the potential of network-PIM components for obtaining much more stable gas separation performance over extended periods of time.

THE PREVENTIVE EFFECT OF SIROLIMUS ON URETERAL STRICTURE FORMATION

Introduction: Stricture of the transplant kidney ureter occurs in approximately 3% of transplant recipients. Risk factors for ureteral stricture include kidneys coming from marginal donors with advanced age and multiple comorbidities. Additionally, delayed graft function, presence of multiple renal arteries and direct injury during retrieval may increase the risk of this complication. Its clinical presentation is typical with elevated serum creatinine accompanied by hydronephrosis. Although several open and endoscopic techniques have been described to manage this condition, ureteral stricture still increases short and long-term graft loss significantly. An M-TOR inhibitor Sirolimus has been shown to reduce fibrosis. Since the mechanism of stricture formation is also through fibrosis, we analyzed the effect of this immunosuppressive drug on the prevention of ureteral strictures. Methods: 32 New Zealand White rabbits (2500-3000grams) were used in the study. The rabbits were randomly assigned into four groups (n=8). Group 1: A unilateral nephrectomy and subsequent full transection of the contralateral ureter was performed. The transected ureter was reconstructed over a double J ureteral stent by using interrupted 7/0 PDS stitches. Group 2: Same procedure with group 1 with Sirolimus- impregnated (1mg) stent placement Group 3: A unilateral nephrectomy and subsequent full transection of the contralateral ureter was performed. The transected ureter was reconstructed without a stent and 1 ml of saline was instilled over the anastomosis. Group 4: Same with group 3 with 1ml (1mg/ml) of Sirolimus solution instilled over the ureteric anastomosis (Figure 1). On postoperative day 3, serum creatinine levels were measured. On postoperative day 7, an ultrasound of the kidney was performed to evaluate hydronephrosis. On postoperative day 21, all rabbits were explored to evaluate the ureteral anastomosis. Subsequently, all subjects were terminated, and full segment of the ureter was removed for histopathology assessments and tissue hydroxyproline level measurements. Results: Severe hydronephrosis and creatinine elevation were observed in group 3 compared to other groups (Figure 2). Histopathological evaluation of the specimens showed increased fibrosis scores in groups 1 and 3 (Figures 3&4). Tissue hydroxyproline levels in group 4 were found to be lower compared to other groups. Conclusion: Sirolimus-impregnated double J stents may decrease ureteric stricture formation. This effect can be beneficial both in both kidney transplant and endourology practice.Fig. 1.Fig. 2.Fig. 3.

1 -YEAR PROTOCOL BIOPSIES IN PEDIATRIC KIDNEY TRANSPLANT CHILDREN: ARE UNFAVORABLE HISTOLOGICAL LESIONS RELATED TO NO ADHERENCE?

Introduction: In adult recipients histological findings in surveillance biopsies at 1-year post kidney transplantation (KT) correlate independently with short and long-term graft survival. Donor specific antibodies (dnDSA) are associated with antibody- mediated rejection. Non-adherence (NOA) to treatment, is a risk factor for dnDSA. Studies in children with KT with protocol biopsies are scarce. Objective: To evaluate the prevalence of favorable (FAV) and unfavorable (UNFAV) histological lesions (FAV) for graft survival in 1-year protocol biopsies of KT children and to identify risk variables for these lesions. Methods: Prospective cohort study in all recipients of a 1st KT between 06/01/2018 and 05/30/2019. (TABLE 1) According to their histological risk, lesions were grouped in “FAV” and “UNFAV”. “FAV” lesions were: 1) minor morphological changes, with absence of inflammation and / or fibrosis and / or chronic glomerulopathy or glomerulonephritis, 2) Acute Interstitial inflammation without interstitial fibrosis or glomerular changes 3) Mild Interstitial fibrosis with absence of interstitial inflammation. “UNFAV” lesions were: 1) moderate-severe interstitial fibrosis without inflammation 2) acute or chronic active rejection mediated by antibodies or T cells 3) de novo glomerular disease 4) polyoma virus-associated nephropathy. dn-DSA were sought simultaneously with kidney biopsy. TAC and / or SRL variation coefficient (VC) >25% was considered a surrogate of NOA. Results: 38 children were included. 29 had “FAV” lesions (76%): 23, Minimal morphological changes, and 6 mild fibrosis. Nine had “UNFAV” histology (24%): One had disease recurrence, three acute vascular rejection, (2/3 subclinical rejection; 1/3 DSA+) and four had moderate fibrosis (2 had graft hydronephrosis and 2 had previous AR,1DSA+). Mean eGFR in patients with “UNFAV” lesions was 39 ± 12.1 ml / min/ 1.73m2 vs 65.3 ± 18 ml / min / 1.73m2 in those with “FAV” (p=0.0003). Both groups had similar pre KT clinical and demographic characteristics. (TABLE2). UNFAV patients had higher incidence of previous Acute Rejection (TABLE2). TAC or SRL VC was: < 25% in 71% of patients (n= 27), and > 25% in 19% of patients (n=11), those with irregular intake. Children with VC> 25% had higher risk of an “UNFAV” lesion in protocol biopsy (OR: 4.8; p=0,04) and higher prevalence of dnDSA (18% vs 0%; p=0.02) Conclusion: In this cohort, FAV lesions were the most prevalent and were associated with negative dnDSA and TAC or SRL VC <25%. Children with UNFAV lesions had lower eGFR. Those with TAC or SRL VC>25% had higher risk of an “UNFAV” lesion, and higher prevalence of dnDSA. Follow-up of this cohort is imperative.

In-Block Lateralization as a New Technique for Mobilization of the Inferior Alveolar Nerve: A Technique Case Series.

The edentulous atrophic posterior mandible is often a great challenge for implant rehabilitation. Although a number of treatment options have been proposed, including the use of short implants and surgical grafting techniques, in cases of severe bone atrophy, techniques for mobilization of the inferior alveolar nerve (IAN) have been shown to be efficient, with good results. Four female patients underwent IAN lateralization for prosthetic rehabilitation of the posterior mandible from 2013 to 2019, with 3 years to 5 years and 3 months of follow-up. This case series describes a new technique for mobilization of the IAN, named in-block lateralization, to facilitate access to the IAN and to reduce nerve manipulation. The implant is immediately installed (allowing nerve lateralization in unitary spaces), and the original mandibular anatomy is restored with autogenous bone from the original bed during the same surgical procedure. When well indicated and well performed, this new approach provides better and easier visualization of the IAN and safer manipulation aiming to achieve good results for implant stability and minimal risk of neurosensory disturbances, allowing rehabilitation even in unitary spaces.

Living with Breakthrough: Two-Dimensional Liquid-Chromatography Separations of a Water-Soluble Synthetically Grafted Bio-Polymer

In this study, we evaluate the use of various two-dimensional liquid chromatographic methods to characterize water-soluble, synthetically grafted bio-polymers, consisting of long poly(acrylic acid) chains and short maltodextrin grafts. The confirmation of the presence of grafting and the estimation of its extent is challenging. It is complicated by the limited solubility of polymers, their structural dispersity and chemical heterogeneity. Moreover, the starting materials (and other reagents, reaction products and additives) may be present in the product. Reversed-phase liquid chromatography (RPLC), hydrophilic-interaction liquid chromatography (HILIC) and size-exclusion chromatography (SEC) were used to characterize the product, as well as the starting materials. Additionally, fractions were collected for off-line characterization by infrared spectroscopy and mass spectrometry. The one-dimensional separation methods were found to be inconclusive regarding the grafting question. Breakthrough (the early elution of polymer fractions due to strong injection solvents) is shown to be a perpetual problem. This issue is not solved by comprehensive two-dimensional liquid chromatography (LC × LC), but information demonstrating the success of the grafting reaction could be obtained. SEC × RPLC and HILIC × RPLC separations are presented and discussed.

Expanding the Utilization of Kidneys from Donors with Acute Kidney Injury

Our aim is to review the experience with transplanting kidneys from decreased donors with acute kidney injury (AKI). The discard rate is higher for kidneys from AKI donors. Studies have uniformly shown that the risk of delayed graft function (DGF) is higher. However, the majority of studies have shown that other outcomes including short and long graft survival, eGFR, and risk of rejection are not inferior with transplanting AKI donor kidneys. To select AKI donor kidneys, we depend on preimplantation biopsy to exclude AKI kidneys with > 10% cortical necrosis or more than mild chronic changes. Although the DGF rate is higher, we have been able to safely discharge patients by POD 2 and manage DGF as an outpatient. It is estimated that if the transplant community used appropriately selected kidneys from AKI donors, there would be almost 600 additional transplants done each year in the US.

Should We Perform Old-for-Old Kidney Transplantation during the COVID-19 Pandemic? The Risk for Post-Operative Intensive Stay.

Health care systems worldwide have been facing major challenges since the outbreak of the SARS-CoV-2 pandemic. Kidney transplantation (KT) has been tremendously affected due to limited personal protective equipment (PPE) and intensive care unit (ICU) capacities. To provide valid information on risk factors for ICU admission in a high-risk cohort of old kidney recipients from old donors in the Eurotransplant Senior Program (ESP), we retrospectively conducted a bi-centric analysis. Overall, 17 (16.2%) patients out of 105 KTs were admitted to the ICU. They had a lower BMI, and both coronary artery disease (CAD) and hypertensive nephropathy were more frequent. A risk model combining BMI, CAD and hypertensive nephropathy gained a sensitivity of 94.1% and a negative predictive value of 97.8%, rendering it a valuable search test, but with low specificity (51.1%). ICU admission also proved to be an excellent parameter identifying patients at risk for short patient and graft survivals. Patients admitted to the ICU had shorter patient (1-year 57% vs. 90%) and graft (5-year 49% vs. 77%) survival. To conclude, potential kidney recipients with a low BMI, CAD and hypertensive nephropathy should only be transplanted in the ESP in times of SARS-CoV-2 pandemic if the local health situation can provide sufficient ICU capacities.

Safe and effective elongation of a short graft and multiple renal veins using the gonadal vein (cylindrical technique) in living donor kidney transplantation

BackgroundThe use of laparoscopy is increasing in various surgical disciplines, including living donor kidney transplant (LDKT). In laparoscopic transplants, vessel length of the donor kidneys often falls short. This makes anastomosis to the recipient's external iliac vein difficult, which may cause problems when blood circulation reconstruction is required. Renal vein elongation (RVE) is often needed, but the available materials may fall short in terms of post-transplant vessel function. Objective and methodsWe aimed to determine whether the gonadal vein was a viable option for RVE in LDKT. We therefore performed LDKT in three cases wherein RVE was performed using the gonadal vein. We used the cylindrical method wherein the donor's gonadal vein was shaped into a cylinder, and the vessel was extended end-to-end with the renal vein. ResultsAll cases showed immediate graft function after surgery. The total ischemic time was 151, 168, and 169 min in cases 1, 2, and 3, respectively. The serum creatinine levels at discharge were 0.98 mg/dL, 2.07 mg/dL, and 1.16 mg/dL in cases 1, 2, and 3, respectively. None of the patients developed any complications during their hospital stay. ConclusionSince the renal vein was extended using a gonadal vein, vessel suturing with the external iliac vein became easier; as a result, bleeding and outflow block could be prevented.

Management of Sciatic Nerve Defects

Management of sciatic nerve injuries can be difficult for surgeons without a special interest in nerve surgery as they would only treat a handful of such cases for many years. Sciatic nerve defects pose the greatest repair challenges, with nerve grafting producing mixed results because of the large size of the nerve in both diameter and length. This article first presents the peculiarities of sciatic nerve defects management, based on the authors experience and a literature review. Various issues are dealt with: When to operate depending on the injury mechanism? What are the results of nerve autografting and allografting? On which component should the repair focus in very large defects? Subsequently, alternatives to conventional nerve grafting are proposed. The authors stress the usefulness of direct nerve suture with knee flexion at 90 degrees, which permits bridging of gaps as much as 8 cm in length. For larger defects, other procedures should be considered: long vascularized nerve grafting in complete lesions, short grafting with knee flexed, or tendon transfers in partial lesions.

Use of the short saphenous vein graft in microsurgical reconstruction.

Use of the short saphenous vein graft in microsurgical reconstruction.

Biomechanical comparison of the use of different surgical suture techniques for continuous loop tendon grafts preparation

We introduce a new approach for a continuous loop tendon-graft preparation, benchmarking it against established graft preparation techniques widely used in conjunction with non-adjustable interference screw fixation. A four-strand bovine tendon graft was prepared using the following graft preparation techniques: standard graft using the baseball stitch technique (M-tech group); continuous loop graft using the GraftLinkTM technique (Arthrex-tech group); continuous loop graft using the Kessler anastomosis technique (Kessler-tech group); and continuous loop graft using a Double-Z anastomosis technique (Double Z-tech group). Each group of eight specimens underwent cyclic loading followed by a load-to-failure test. The M–technique yielded a smaller graft diameter (8.4 ± 0.5 mm) compared to the statistically equivalent diameters of the three continuous loop techniques (8.9 ± 0.6 mm of Arthrex-tech group, 9.1 ± 0.4 mm of Kessler-tech group and 9.2 ± 0.6 mm of Double Z-Tech group). The continuous loop grafts formed by the Double Z-Technique showed outstanding performance among the tested techniques in terms of ultimate failure load (982 ± 121 N) and cyclic elongation (3.7 ± 1.0 mm). There was no significant difference between the four groups in cyclic stiffness. Of the assessed techniques, the Arthrex technique resulted in the lowest ultimate elongation (2.0 ± 0.7 mm), followed by the Double Z-tech (4.5 ± 1.8 mm), the M-tech (5.2 ± 3.9 mm), and the Kessler-tech (5.3 ± 2.4 mm). The Arthrex-tech group (5.98 ± 0.38 min) displayed the shortest graft preparation time, followed by the M-Tech (7.94 ± 0.58 min), Kessler-tech (9.03 ± 0.39 min) and Double Z-Tech (13.29 ± 1.14 min). Double Z-Tech can improve the construct of continuous loop tendon graft with regard to mechanical performance.

Controllably coated graphene oxide particles with enhanced compatibility with poly(ethylene-co-propylene) thermoplastic elastomer for excellent photo-mechanical actuation capability

This paper reports the utilization of the controllable coating via SI-ATRP technique as a promising approach for controlling stimuli-responsive capabilities of graphene oxide (GO) based nanocomposites. Various polymer brushes with controlled molar mass and narrow dispersity were grown from the surface of GO particles. Modification of GO with poly(methyl methacrylate) and poly(n-butyl methacrylate) was proved by transmission electron microscopy, thermogravimetric analysis with online FTIR recording and finally by X-ray photoelectron spectroscopy (XPS). Densities of GO-based materials were investigated and conductivity measurements showed the increase values. XPS and Raman shift was used to confirm the GO particles reduction. A compatibility of the filler with propylene-based elastomer was elucidated by melt rheology. The light-induced actuation capability was investigated on composite samples to show, that polymer hybrid particles based on GO have better compatibility with the polymer matrix and thus their proper dispersibility was significantly improved. In addition the plasticizing effect of the short polymer grafts present on the GO filler surface has the crucial impact on the matrix stiffness and thus the ability of composite material to reversibly respond to the external light stimulation.

Radial nerve injuries and outcomes: Our surgical experience.

The aim of this study was to retrospectively evaluate patients who underwent surgery in our department for radial nerve lesions in terms of surgical outcomes. Thirty-eight patients were admitted to our department with radial nerve lesion. Twenty-seven of the patients had entrapment neuropathy and 11 had radial nerve injury secondary to other traumas. Various factors such as surgical results, time to surgical intervention, injury mechanism, and reconstruction technique were analyzed. In all of 27 patients who were operated for radial nerve entrapment neuropathy, a complete improvement in wrist dorsal flexion was detected at postoperative 3rd month. Seven of the 11 patients who were operated for radial nerve lesion had different degrees of improvement in wrist dorsal flexion at the postoperative 3rd month. Two of the seven patients underwent anastomosis using a sural nerve graft. The recovery rate in our series was 89%. Three of the 4 patients who did not recover after the radial nerve injury were the patients who were operated within the 1st month after the trauma. Better functional results were obtained in the postoperative period in patients who were operated after the 1st month, underwent internal neurolysis and used a short nerve graft for anastomosis in the radial nerve lesions. In patients with entrapment neuropathy, the earliest surgery revealed satisfactory results in the postoperative period.