Short Graft Research Articles

A Last Resort: Dacron Vascular Graft Prosthesis for Management of a Blowhole Colostomy.

The creation of a blowhole colostomy can be an effective option for patients with large bowel obstruction and severe abdominal disease. However, they are often difficult to manage secondary to poor appliance fitting, peristomal dermatitis, and pain. In 2021, a case series describing a novel technique using a Dacron Vascular Prosthesis (VUP medical, Brno, Czech Republic) sutured to the mucocutaneous junction to help with stoma management was described. In the following case study, we share our experience with placement of a Hemashield Gold Dacron Graft (Maquet Cardiovascular, LLC, Wayne, NJ, USA) as a last resort in the management of a blowhole colostomy in a patient with large bowel obstruction secondary to metastatic carcinoid tumor. Compared to the previously described technique, we used a shorter graft, non-absorbable suture (Nylon, Ethicon, Cincinnati, OH, USA) and took larger bites of the mucocutaneous junction to achieve improved quality of life.

All-inside Technique versus Conventional Full-tunnel Reconstruction for Anterior Cruciate Ligament Tears of the Knee: A Systematic Review and Meta-analysis

Introduction: There is a paucity of evidence in literature regarding the efficacy of all-inside anterior cruciate ligament reconstruction (AIACLR) vis-à-vis the traditionally used full-tunnel (FT) technique. The primary aim of this review, thus, was to shed light on this discrepancy and determine which of the two methods had more optimum results. Methods: PubMed and Cochrane Library databases were systematically searched by two independent reviewers. Selection criteria were laid down as per the patient, intervention, control, and outcome (PICO) format. All included studies were checked for quality and methodological strength using well-defined risk-of-bias assessment tools. Techniques were compared with respect to their graft and tunnel dimensions, functional outcome scores, and complication rates. Data analysis was carried out using the RevMan 5.3® software. Results: A total of 12 articles (six randomized control trials or randomized clinical trials and six prospective/retrospective cohort studies) with 880 knees were included in this study. In most instances of AIACLR, a short and thick quadrupled semitendinosus graft was used for reconstruction. Suspensory fixation devices alone or in combination with interference screws were used for graft fixation. The two techniques were comparable in terms of their functional outcomes, with a slightly lower graft failure rate with AIACLR. Conclusion: The AI technique provides a safe and reliable alternative to conventional ACLR in terms of comparable functional results, reduced postoperative pain, and lower graft failure rates. However, more comparative trials with long-term follow-ups are needed before a definitive statement can be put forward.

802. TECHNICAL DETAILS: FREE JEJUNAL GRAFT AND REVERSE SAPHENOUS VEIN GRAFT FOR RECONSTRUCTION AFTER TOTAL PHARYNGO-LARYNGECTOMY AND PROXIMAL ESOPHAGECTOMY

Abstract Background We would like to show our tips for free jejunal graft and vascular reconstruction after pharyngo-laryngectomy and proximal esophagectomy. Methods 65 years-old man with history of hypopharynx squamous cell carcinoma cT3 cN0 cM0 who underwent radical Qt/Rt with initially complete response. After 2 years follow-up, he presented dysphagia and recurrence of squamous cell carcinoma proven by histology. Upper endoscopy shows cervical esophageal stenosis due to tumor infiltration. Rescue surgery was decided after systemic dissemination was ruled out with PET-CT. Results Pharyngo-laryngectomy, total thyroidectomy and proximal esophagectomy was performed. Free margin tumor was confirmed by frozen section. Jejunal segment with adequate vascular supply is selected, preferable with a single artery and vein. Peristaltic direction of the jejunum is marked to avoid mistakes during graft transposition. Division of mesenteric branches to prevent postoperative bleeding. Before jejunal section we recommend administration of hyoscine butilbromide 20 mg iv to avoid jejunal spams. Measuring the length graft needed before dividing the jejunum to avoid redundant or short graft is recommended. We must carefully isolate the pedicle avoiding damaging blood supply. To reduce time of ischemia, jejunal graft pedicle should not be ligated until cervical dissection is completed and we have ruled out if venous graft may be needed. After cervical artery and vein dissection, we ensure adequate blood flow and heparinize vessels before clipping. When dividing the pedicle, artery should be divided before the vein to avoid venous congestion, posteriorly we must heparinize the vessels. Povidone-iodine intraluminal washing is recommended. Jejuno-jejunal anastomosis for GI tract restoration. GI reconstruction first is recommended to avoid unnecessary traction on the vascular anastomosis. After ensuring adequate direction of the jejunal graft jejuno-esophageal anastomosis is performed with interrupted suture. Pharyngo-jejunal anastomosis is performed with barbed 3-0 running suture for anterior and posterior layer. Methylene blue test is performed for check the anastomosis. Vascular reconstruction technique depends on the vascular anatomical variations and availability. In this case, superior thyroid artery and sublingual vein were available. Saphenous vein graft might be needed, this graft must be used in reverse way to avoid the vein valves and length must be adjusted. Venous anastomosis should be performed before than arterial reconstruction after heparinize solution in both vessels to avoid thrombosis. Conclusion Free jejunal graft is a highly complex procedure that must be extremely coordinated and protocolized to avoid longer time of ischemia and risk of thrombosis that might compromise the graft viability. https://1drv.ms/v/s!AmFrct07P6MP1Fbyh_7Ce_OK5bB8?e=OMSjsK

Improved Preservation of Rat Small Intestine Transplantation Graft by Introduction of Mesenchymal Stem Cell-Secreted Fractions.

Segmental grafts from living donors have advantages over grafts from deceased donors when used for small intestine transplantation. However, storage time for small intestine grafts can be extremely short and optimal graft preservation conditions for short-term storage remain undetermined. Secreted factors from mesenchymal stem cells (MSCs) that allow direct activation of preserved small intestine grafts. Freshly excised Luc-Tg LEW rat tissues were incubated in preservation solutions containing MSC-conditioned medium (MSC-CM). Preserved Luc-Tg rat-derived grafts were then transplanted to wild-type recipients, after which survival, injury score, and tight junction protein expression were examined. Luminance for each graft was determined using in vivo imaging. The findings indicated that 30-100 and 3-10kDa fractions of MSC-CM have superior activating effects for small intestine preservation. Expression of the tight-junction proteins claudin-3, and zonula occludens-1 preserved for 24h in University of Wisconsin (UW) solution containing MSC-CM with 50-100kDa, as shown by immunostaining, also indicated effectiveness. Reflecting the improved graft preservation, MSC-CM preloading of grafts increased survival rate from 0% to 87%. This is the first report of successful transplantation of small intestine grafts preserved for more than 24h using a rodent model to evaluate graft preservation conditions that mimic clinical conditions.

Free Flaps in Patients with Advanced Arteriosclerosis of the Tibial Vessels: Mini Vein Graft to the Peroneal Artery.

Lower extremity reconstruction with free flaps in patients with only peroneal artery runoff remains a challenge. Here, we present a novel technique for reconstruction of medial defects in the distal leg using a medial approach to the peroneal artery and a short interposition vein graft anastomosed end to side to the peroneal artery. A retrospective, single-center study was performed including all patients who underwent lower extremity reconstruction with free flaps anastomosed to the peroneal artery using a mini vein graft from November 2020 to March 2022. The primary outcome measure was limb salvage. Secondary endpoints were flap survival and postoperative complications. Seven patients received lower extremity free flap reconstruction with a mini vein graft to the peroneal artery. Flap loss rate was 0%. Limb salvage was achieved in five patients (71%). At 6-month follow-up, all patients were ambulatory. One patient died 1 month after surgery due to heart failure. Mini vein graft to the peroneal artery allows reliable and safe free flap reconstruction of distal leg defects in patients with only peroneal artery runoff.

Concentrated O/W Emulsion Stability of Non-Ionic Chitosan Oligomer Surfactants Modified by Epoxidized Fatty Chains at pH7: Influence of Emulsification Conditions

In this study, chitosan-based surfactants were synthesized by epoxy–amine chemistry to stabilize concentrated O/W emulsions at pH7. Chitosan was first depolymerized by nitrous deamination to obtain chitooligosaccharides (COS) with degrees of polymerization of 10 (DP10) and 20 (DP20). Then, three different epoxidized fatty chains, i.e., octyl/decyl glycidyl ether (C9), hexadecyl glycidyl ether (C16) and epoxidized cardanol (card), were grafted onto the amine groups of chitosan to form six amphiphilic structures. NMR measurements revealed grafting efficiencies ranging from 1 to 30% while HLB values ranged from 13 to 20. The relationships between these surfactant structures and their adsorption properties were investigated by tensiometric measurements, highlighting the need for a short hydrophilic moiety and high grafting efficiency to obtain the best adsorption. Subsequently, concentrated O/W emulsions (66% of oil) at pH7 were produced using COS-based surfactants and the impact of stirring time and speed during the emulsification process was described through rheological, droplet size and microscopy measurements. Finally, emulsions were stored over 2 months in order to study the destabilization phenomenon into the mixture, i.e., coalescence and creaming, by using laser granulometry and Turbiscan. Results demonstrated that stability could be enhanced by increasing emulsion viscosity, reducing droplet size or optimizing the adsorption layer at the O/W interfaces.

Comparison of the retear rate 2 years after ACL reconstruction with the Tape Locking Screw short graft system and the STG technique: A case control study with propensity score matching

PurposeTheoretically, short semitendinosus grafts result in less pain and morbidity while providing greater knee flexion strength and sparing the gracilis tendon. They often require the use of blind bone tunnels as well as fixation at both ends of the graft with suspensory cortical buttons. The “Tape Locking Screw” (TLS) system is another option. There are few studies comparing ACL reconstruction with a short graft using the 4-strand semitendinosus graft (ST4-TLS) technique with that of the semitendinosus-gracilis (STG) procedure. This study was designed: (1) to compare the retear rate following these two technics after 2years of follow-up, (2) to compare the clinical scores, complications and return to sport times between the two procedures Q1, Q2. HypothesisOur hypothesis was that there would be no differences in retear rates between the two techniques. MethodsThis single center case control study included 290 patients who underwent STG reconstruction that were paired by propensity score matching to 299 patients who underwent ST4-TLS reconstruction. The main evaluation criterion was the retear rate 2years after surgery. Secondary criteria were the two-year postoperative complication rate, the time to return to sport, to pivot sports and to running, as well as the complication rates and clinical scores 6months, 1year and 2years after surgery. ResultsAt the final follow-up, the overall retear rate in our series of ACL ligament reconstruction was 6.0% (36/596). There was no difference in retear rates between the groups 2years after ligament reconstruction [ST4-TLS: 6.7% (20/299) vs. STG: 5.4% (16/297); p=0.47]. The postoperative KOOS symptom score and the Tegner score were found to be better in the STG group at 1year (81 vs. 78, p=0.008) and 2years (5.64 vs. 5.10, p=0.016), respectively, representing the minimally clinically important difference (MCID) for the latter. No difference was found in the other clinical scores 6months, 1year or 2years after surgery. There was no significant difference in the return to sport [TLS: 93.0% (164/299) vs. STG: 93.0% (158/297) p=0.99] or the complication rate [TLS: 8.7% (26/299) vs. STG: 7.4% (22/297) p=0.89] between the groups. DiscussionThe ST4-TLS ACL ligament reconstruction technique was found to be as reliable as the standard STG procedure 2years after surgery for the retear rate and the return to sport, although the results of certain postoperative clinical scores seem to be lower. Level of evidenceIII; case control study.

Micro-ballistic response of thin film polymer grafted nanoparticle monolayers.

Self-assembled polymer grafted nanoparticles (PGNs) are of great interest for their potential to enhance mechanical properties compared to neat polymers and nanocomposites. Apart from volume fraction of nanoparticles, recent experiments have suggested that nanoscale phenomena such as nanoconfinement of grafted chains, altered dynamics and relaxation behavior at the segmental and colloidal scales, and cohesive energy between neighboring coronas are important factors that influence mechanical and rheological properties. How these factors influence the mechanics of thin films subject to micro-ballistic impact remains to be fully understood. Here we examine the micro-ballistic impact resistance of PGN thin films with polymethyl methacrylate (PMMA) grafts using coarse-grained molecular dynamics simulations. The grafted chain length and nanoparticle core densities are systematically varied to understand the influences of interparticle spacing, cohesion, and momentum transfer effects under high-velocity impact. Our findings show that the inter-PGN cohesive energy density (γPGN) is an important parameter for energy absorption. Cohesion energy density is low for short grafts but quickly saturates around entanglement length as adjacent coronas interpenetrate fully. The response of γPGN positively influences specific penetration energy, , which peaks before chain entanglement starts (<Ne). We further divide the ballistic response into three regimes based on grafted chain length: short graft, intermediate graft, and entangled graft. The short grafted PGNs show fragmentation due to almost no cohesion between particles, and the rigid body motion of the nanoparticles absorbs most of the energy. When chains are in the intermediate graft length regime, the film fails by chain pull-out, and unraveling of grafts is the primary dissipation mechanism. The Ashby plot of penetration energy, Ep, indicates ballistic processes are inelastic collisions when grafted chains are short and vary with density in a power law fashion as expected from momentum transfer. The response indicates that a lower nanoparticle weight fraction, ϕwtNP, leads to higher energy absorption per mass, that is, the added mass of nanoparticles does not warrant proportionate increases in energy absorption in the parametric range studied. However, the peak deceleration, Ab, shows a clear positive effect of adding NPs. Finally, PGNs with intermediate chain lengths simultaneously show relatively higher and Ab.

Rare Median Nerve and Digital Nerve Tumor Resection and Distal Nerve Transfers: A Report of 2 Cases.

We present 2 cases of median nerve reconstruction using distal nerve transfers after resection of unusual benign median nerve tumors. Critical sensation was restored in case 1 by transferring the fourth common digital nerve to first web digital nerves. Thumb opposition was regained by transferring the abductor digiti minimi ulnar motor nerve branch to the recurrent median motor nerve branch. Critical sensation was restored in case 2 by transferring the long finger ulnar digital nerve to the index finger radial digital nerve. Distal nerve transfers, even with short grafts, are reliable median nerve deficit treatments, sparing the need for larger autologous nerve grafts and late tendon opponensplasties.

Computational investigation of the effects of polymer grafting on the effective interaction between silica nanoparticles in water.

Understanding and control of the effective interaction between nanoscale building blocks (colloids or nanoparticles) dispersed in a solvent is an important prerequisite for the development of bottom-up design strategies for soft functional materials. Here, we have employed all-atom molecular dynamics simulations to investigate the impact of polymer grafting on the solvent-mediated effective interaction between the silica nanoparticles (Si-NPs) in water, and in turn, on its bulk structural and thermodynamic properties. We found that the nature of the short grafting polymers [characterized by their interaction with water (hydrophobicity or hydrophilicity) and molecular weight] has a profound effect on the range and strength of the effective interaction between the Si-NPs. The hydrophobic polymer [such as polyethylene (PE)]-grafting of Si-NP gives rise to a more attractive interaction between the Si-NPs compared to the hydrophilic polymer [such as polyethylene glycol (PEG)] and non-grafted cases. This study further provides fundamental insights into the molecular origin of the observed behavior of the effective pair interactions between the grafted Si-NPs. For PE-grafted Si-NPs, the confined water (water inside the cavity formed by a pair of Si-NPs) undergoes a partial dewetting transition on approaching below a critical inter-particle separation leading to a stronger attractive interaction. Furthermore, we report that the effective attraction between the PE-grafted Si-NPs can be reliably controlled by changing the grafting PE density. We have also investigated the bulk structural and thermodynamic behavior of the coarse-grained Si-NP system where the particles interact via effective interaction in the absence of water. We believe that the insights gained from this work are important prerequisites for formulating rational bottom-up design strategies for functional materials where nano- (or, colloidal) particles are the building blocks.

How does the precursor backbone length affect the grafting efficiency and kinetics for bottlebrush polystyrenes prepared by graft-onto Strategy?

The clarification of the potential dependence of grafting efficiency on the backbone length during the graft-onto reaction process is extremely important for subsequent structure–property study. In this work, by using alkyne-functional polypropargyne acrylate (PPANb, Mw/Mn < 1.10 and Nb = 960, 193, 35) and azide-functional polystyrene (PSNs, Mw/Mn < 1.15 and Ns = 54, 38, 22) as the backbone and sidechain precursors, we have investigated the Nb-dependence of the grafting reaction during the graft-onto click process. Specifically, the influence of solution concentration and feed ratio are investigated, and a combination of SEC characterization, Gaussian fitting and theoretical analysis is used to estimate the Nb-dependent grafting reaction for the bottlebrush product (PPANb-g-PSNs). The main findings include: 1) when the reaction time (t) is sufficient long (t = 24 h), the grafting efficiency is found to be nearly irrelevant with Nb, even if we consider 2 ∼ 5 times of difference in the diffusion coefficient (D) based the well-known scaling relation of D ∼ Nb1/2 in the semidilute reaction solution; 2) the time-dependent kinetics investigation further shows abnormal and different pathways for different backbone lengths when 0 min < t < 10 min, but the final grafting efficiency determined at t = 300 min shows no much difference, going back to the preliminary result of equilibrium state at t = 24 h; 3) the origin of abnormal pathways may be attributed to the relatively poor signal-to-noise ratio and potential dependence of dn/dC of PPANb-g-PSNs product on the composition at low grafting density range, which needs clarification in future. For the first time, our result has unambiguously demonstrated that, for a mixed solution of reaction system composed of backbone precursors with their lengths differing by hundreds of times, the polydispersity effect of the backbone length does not affect the final grafting efficiency during the process, no matter for long or short sidechain grafts. The result implies that it is the local dynamics of chain segments, instead of the overall translational diffusion dominates the graft-onto process in the concentration-regime studied.

Integration of a Custom-Made Fenestration to Simplify Acute Reno-Visceral In Situ Aortic Repair.

To illustrate the technique of antegrade in situ laser fenestration (ISLF) on a predesign custom-manufactured stent-graft with single reinforced fenestration for use in emergency endovascular repair of complex abdominal aortic aneurysms (AAAs). A short custom-made device (CMD) fenestrated graft was predesigned with a single preloaded 8 mm strut-free fenestration at 12 o'clock position. A modified preloaded system was used to allow unilateral access from the distal port if necessary. After bilateral percutaneous femoral access, the graft was deployed under fusion guidance with the CMD fenestration matching the superior mesenteric artery (SMA) origin and immediately bridged as per standard technique. The aneurysm was then excluded with a bifurcated device. A large steerable sheath was used to allow for sequential antegrade laser in situ fenestration and stenting of the renal arteries. Single-vessel customized short fenestrated grafts for the SMA and antegrade in situ laser renal fenestrations are technically feasible for repair of acute complex AAAs even after previous infrarenal reconstruction. It could become an off-the-shelf solution to limit aortic coverage and reno-visceral ischemia, even in patients with a narrow aortic diameter at the renal level. Single-vessel precustomized short fenestrated grafts for the SMA combined with renal artery antegrade ISLF can be a feasible option for the acute repair of patients with complex aneurysms and a narrow aortic diameter at the reno-visceral segment. It may limit aortic coverage and reno-visceral ischemic time and also be applicable after previous infrarenal endovascular aneurysm repair (EVAR).

Influence of side chain lengths in mechanophore‐containing polyisobutylene‐graft‐polystyrene

AbstractPolymer architecture plays an important role in morphology and mechanochemical response. Here, graft copolymers containing mechanophores at the backbone‐arm junction are synthesized through a combination of post‐polymerization modification of butyl rubber and controlled radical polymerization. A series of graft copolymers with 70:30 or 50:50 polyisobutylene:polystyrene (PIB:PS) volume fractions were synthesized by changing the grafting density and arm length to keep the volume fractions constant. The morphologies for these polymers are disordered but show a decreasing domain size with shorter arm lengths, and the samples with a greater number of PS side chains show greater domain mixing. Using pulsed ultrasound experiments, we found greater backbone scission occurs for polymers with a greater number of short grafts per chain than the long grafts with fewer grafting points. Finally, mechanophore activation is greater for samples with arm molecular weights ≥13 kg/mol, attributed to exceeding the cutoff molecular weight for PS.

Vascular reconstruction related to the extracranial vertebral artery: the presentation of the concept and the basis for the establishment of the bypass system.

The intracranial vertebrobasilar artery system has a unique hemodynamic pattern (vessel trunk converged bilateral flow with three groups of perforators directly arising from it), is embedded within intense osseous constraints, and is located far from conventional donor vessels. Two major traditional modalities of posterior circulation revascularization encompass the superficial temporal artery to the superior cerebellar artery and the occipital artery to the posteroinferior cerebellar artery anastomosis, which are extracranial-intracranial low-flow bypass with donor arteries belonging to the anterior circulation and mainly supply focal perforators and distal vascular territories. As our understanding of flow hemodynamics has improved, the extracranial vertebral artery-related bypass has further evolved to improve the cerebral revascularization system. In this article, we propose the concept of "vascular reconstruction related to the extracranial vertebral artery" and review the design philosophy of the available innovative modalities in the respective segments. V1 transposition overcomes the issue of high rates of in-stent restenosis and provides a durable complementary alternative to endovascular treatment. V2 bypass serves as an extracranial communication pathway between the anterior and posterior circulation, providing the advantages of high-flow, short interposition grafts, orthograde flow in the vertebrobasilar system, and avoiding complex skull base manipulation. V3 bypass is characterized by profound and simultaneous vascular reconstruction of the posterior circulation, which is achieved by intracranial-intracranial or multiple bypasses in conjunction with skull base techniques. These posterior circulation vessels not only play a pivotal role in the bypass modalities designed for vertebrobasilar lesions but can also be implemented to revascularize the anterior circulation, thereby becoming a systematic methodology.

Whole Exome Sequencing to Find Candidate Variants for the Prediction of Kidney Transplantation Efficacy.

Kidney transplantation is the optimal treatment strategy for some end-stage renal disease (ESRD); however, graft survival and the success of the transplantation depend on several elements, including the genetics of recipients. In this study, we evaluated exon loci variants based on a high-resolution Next Generation Sequencing (NGS) method. We evaluated whole-exome sequencing (WES) of transplanted kidney recipients in a prospective study. The study involved a total of 10 patients (5 without a history of rejection and 5 with). About five milliliters of blood were collected for DNA extraction, followed by whole-exome sequencing based on molecular inversion probes (MIPs). Sequencing and variant filtering identified nine pathogenic variants in rejecting patients (low survival). Interestingly, in five patients with successful kidney transplantation, we found 86 SNPs in 63 genes 61 were variants of uncertain significance (VUS), 5 were likely pathogenic, and five were likely benign/benign. The only overlap between rejecting and non-rejecting patients was SNPs rs529922492 in rejecting and rs773542127 in non-rejecting patients' MUC4 gene. Nine variants of rs779232502, rs3831942, rs564955632, rs529922492, rs762675930, rs569593251, rs192347509, rs548514380, and rs72648913 have roles in short graft survival.

Drop-off in axonal regeneration along the length of a cross-face nerve graft: An experimental study in rats.

The average nerve graft length utilized in cross-face nerve grafting for reconstruction of facial nerve palsy is 20-22 cm. While the graft length is thought to be one of the greatest determinants of muscle strength, the mechanism through which this happens remains unknown. We studied changes in axonal regeneration along the length of a 2 cm cross-face nerve graft in a rat model. The hypothesis was that axon count would decrease along the length of the graft. A 2 cm nerve graft (sciatic nerve) was used as a cross-face nerve graft in 16 adult female, 210-250 g, Sprague Dawley rats. Thirteen weeks later, 5 mm nerve biopsies were taken at four sites: the facial nerve trunk (control), proximal graft, midpoint of graft (1 cm distal to coaptation) and distal graft (2 cm distal to coaptation). Retrograde nerve labeling with FluoroGold was performed at the biopsied nerve site and the facial motor nucleus was taken 1 week later. Microscopic imaging and manual counting of axons and labeled motor nuclei was performed. Retrograde-labeled motor neuron counts were decreased at the midway point of the graft compared to the facial trunk (1517 ± 335 axons, Δ% = 92.5, p = .01) and even further decreased at the distal end of the graft (269 ± 293 axons, Δ% = 175.5, p = .006). Analysis of the nerve biopsies demonstrated no significant differences in myelinated axon count between the nerve trunk and over the length of the nerve graft (range 6207-7179 axons, Δ% = 14.5, p = .07). In a rat model, the number of regenerating motor neurons drops off along the length of the graft and axon count is preserved due to axon sprouting. How this pattern correlates to ultimate muscle strength remains unknown, but this study provides insight into why shorter grafts may afford better outcomes.

Cyclic vs Linear Bottlebrush Polymers in Solution: Side-Chain Length Effect

Bottlebrush polymers (BBPs) of different architecture are of considerable interest for a broad range of applications, including nanomedicine, electronics, and self-healing materials. Using atomistic molecular dynamics simulations, we investigate and compare the structural and hydration properties of cyclic and linear poly(vinyl alcohol)-graft-poly(ethylene oxide) (PVA-g-PEONsc) BBPs in aqueous solution as functions of PEO side-chain length, Nsc. We find that overall cyclic BBPs are smaller than the corresponding linear BBPs and their shape changes from donutlike to disklike to starlike with increasing side-chain length, while linear BBPs vary in shape from an expanded coil to a rod/cylinder. The radius of gyration of cyclic BBPs increases with an increase of the side-chain length at a somewhat slower rate than the linear BBPs but follows the same scaling Rg ∼ Nsc0.58 in the limit of long side chains. For short grafts, we determine that the persistence length, lp, for both cyclic and linear BBPs increases in a similar manner following an lp ∼ Nsc0.54 dependence. In the long side-chain limit, the persistence length (lp) of cyclic BBP saturates, while for linear BBPs lp strongly increases following the expected scaling relation lp ∼ Nsc15/8. We propose a scaling model that shows that the fraction of side-chains located inside the cyclic BBPs depends on the radius of the backbone ring and significantly decreases with an increase of graft length. For both cyclic and linear BBPs, the hydrogen bonding between PEO side chains and water is somewhat reduced near the backbone, where local chain stretching is observed, while reaching full hydration on the periphery. Overall, the hydration shell within 1 nm of the cyclic BBP backbone is found to be more dynamically stable compared to linear BBPs.

Mid-term and long-term outcomes following heart transplantation with prolonged cold ischemia

Objective: comparative analysis of long-term outcomes following heart transplantation (HT) with prolonged and short cold ischemia.Materials and methods. We analyzed the data of 29 orthotopic HT with &gt;4 hours of cold ischemia. The transplant surgery was performed at Meshalkin National Medical Research Center between 2013 and the present time. Organs were obtained from donors from other regions. The control group consisted of 29 HTs with cold ischemia &lt;4 hours, performed in the same period. The minimum distance between the transplant center and the donor base was about 250 km (Barnaul); the maximum distance was about 850 km (Krasnoyarsk). Recipient survival and postoperative peculiarities were analyzed.Results. In-hospital survival in the prolonged cold ischemia group was 89.7% (n = 26) with 3 deaths (10.3%). In the second group (&lt;240 min), in-hospital survival was 79.3% (n = 23) with 6 (20.7%) deaths. The Kaplan-Meier survival analysis showed no difference between the groups (Log-Rank Test, P 1/4 0.59). In addition, cold ischemia time did not increase the risk of graft rejection and the risk of transplant coronary artery disease (TCAD).Conclusion. HT with cold ischemia &gt;4 hours did not have worse outcomes than in short graft ischemia. This provides grounds for further accumulation of experience in the use of heart donors from remote locations.

Greater Impact of Living Donation Than HLA Mismatching in Short-Term Renal Allograft Survival.

Living donor kidney transplantation (LDKT) is accepted as first-line treatment for patients with end-stage kidney disease with advantages over deceased donor kidney transplantation (DDKT). Still, how the known detrimental effect of HLA mismatch (MM) may hamper these advantages remains unsettled. We sought to determine the effect of the degree of HLA MM, separately in deceased and living donor renal allograft outcomes. We evaluated all adults submitted to LDKT and DDKT at our center between 2006 and 2018. Their HLA MM was classified according to the British Society of Transplantation system in low mismatch (LM) (level 1-2) and high mismatch (HM) (level 3-4). Acute rejection (AR) and global or censored graft survival were the outcomes of interest. Recipients were followed up from transplant until death, graft failure or the end of 2020. Results: One thousand sixty-eight kidney transplant recipients were analyzed, 815 (76%) received a DDKT whereas 253 (24%) received an LDKT. From those submitted to DDKT, 95 (12%) had an LM and 720 (88%) had an HM, whereas in LDKT 32 (13%) had an LM and 221 (87%) had an HM. The AR at one year was 9% in the full cohort. Significant risk factors for AR were HM DDKT (OR:2.3, P=0.047) or HM LDKT (OR:5.6, P=0.003) (LM DDKT as reference), calculated panel-reactive antibody (cPRA) ≥5% (OR:1.9, P=0.040) and delayed graft function (DGF), (OR:3.2, P<0.001). Censored graft survival (CGS) at five years was 96% in the full cohort. Independent predictors for censored graft failure (CGF) were HM LDKT (HR:0.2, P=0.046) (LM DDKT as reference), AR (HR:2.7, P=0.008) and DGF (HR:2.2, P=0.017). Global graft survival (GGS) at five years was 91% in the full cohort. Independent predictors for global graft failure (GGF) were HM LDKT (HR:0.2, P=0.042) (LM DDKT as reference), recipient age (HR:1.8, P<0.001) and DGF (HR:1.8, P=0.006). No AR, CGF or GGF episodes were observed in the LM LDKT group. In our cohort, the level of HLA MM increased the risk of AR independently of donor type. Considering short graft survival, our results support the advantage of living donor vs deceased donor even with an increased HLA MM. However, its effect on long-term graft survival remains to be settled, emphasizing the need for further studies on this matter.

The Short Graft ACL Reconstruction

The Short Graft Anterior Cruciate Ligament (ACL) reconstruction is increasing in popularity. Surgeons are making use of autograft lengths of between 6-6.5 cm for ACL reconstruction. The grafts of choice are the hamstring and quadriceps tendon autograft. The grafts are prepared with cortical fixation on both the femur and tibia ends for cortical fixation. Short tunnels or sockets are reamed instead of full bone tunnels. This helps with bone preservation and the patients have less postoperative pain; but will require special instrumentation for retrograde drilling. The benefit of this technique is improved postoperative hamstring strength with the gracilis preserved, as only the semitendinosus tendon is harvested to obtain a quadrupled ACL graft. The outcomes of short graft ACL reconstruction are comparable to established transportal ACL reconstruction techniques. However, there is a learning curve and additional implant costs involved. The familiarity with the surgical technique, understanding of optimal graft fixation and biology are all paramount to success of this surgery.