Evaluation of a multiphasic parasite clearance profile after treatment of experimental human infection with the investigational anti-malarial M5717 using segmented mixed effect models.

BACKGROUND: Evaluation of parasite clearance patterns in experimental human infection trials helps increase understanding of drug action. In a previously reported phase Ib trial of a new investigational anti-malarial drug M5717, parasite clearance showed a biphasic linear pattern: slow removal phase with a near flat clearance rate followed by a fast clearance phase with a steep slope. In this study three statistical approaches were implemented and compared to estimate the parasite clearance rate for each phase and the time point corresponding to the change of clearance rates (changepoint between the two phases). METHODS: Data using three M5717 doses 150 mg (n = 6), 400 mg (n = 8), 800 mg (n = 8) were used to estimate biphasic clearance rates. Three models were investigated: firstly, segmented mixed models with estimated changepoint-models with/without random effects in various parameters were compared. Secondly, a segmented mixed model using grid search-this method is similar to the first except that changepoints were not estimated, instead they were selected based on model fit from given candidate values. Thirdly, a two-stage approach whereby a segmented regression model fit to each participant followed by a meta-analysis method. Hourly rate of parasite clearance (HRPC) interpreted as the percentage of parasites removed each hour was calculated. RESULTS: The three models generated similar results. Using segmented mixed models, the estimated changepoints after treatment in hours (95% CI) were: 150 mg: 33.9 (28.7, 39.1); 400 mg: 57.4 (52.5, 62.4); and 800 mg: 52.8 (47.4, 58.1). For all three treatment groups, there was nearly no clearance before the changepoints, but rapid clearance in the second phase (HRPC [95% CI]): 150 mg: 16.8% (14.3, 19.1%); 400 mg: 18.6% (16.0, 21.1%); and 800 mg: 11.7% (9.3, 14.1%). CONCLUSIONS: All three statistical approaches are effective tools to characterize the bi-phasic clearance of M5717 in the phase 1b experimental Plasmodium falciparum malaria human infection study. The statistical approaches produced similar results to estimate the two-phase clearance rates and the changepoint for each treatment dose of M5717. However, the segmented mixed model with random changepoints has several advantages: it is computationally efficient, provides precision for changepoint estimates and is robust concerning outlying datapoints or individuals.

Validation of an ovine vesicovaginal fistula model.

INTRODUCTION AND HYPOTHESIS: A representative, large animal model of vesicovaginal fistulas is needed for the training of surgeons and for the development of new surgical techniques and materials for obstetric fistula repair. METHODS: The safety, feasibility, and reproducibility of vesicovaginal fistula creation were studied in 4 adult female sheep. A 1-cm fistula was created between the vagina and the bladder through a transvaginal approach. The defect was allowed to heal for 8 weeks and the animals were then euthanized. The primary outcome was the fistula patency. Secondary outcomes were fistula size, urogenital dimensions, urodynamic evaluation, histology (inflammation, vascularization, collagen deposition) and biomechanical characteristics of the fistula edge (stress at break, maximum elongation, and stiffness). RESULTS: The transvaginal creation of a vesicovaginal fistula was safe. All animals survived the surgical procedure and follow-up period, without complications. Three of the four animals demonstrated a patent vesicovaginal fistula after 8 weeks. Baseline data are provided of the urogenital dimensions and the urodynamic, histological, and biomechanical characteristics of the model. CONCLUSIONS: The ewe is a safe, feasible, and reproducible model for vesicovaginal fistulas. The model can help to study new techniques and materials to boost surgical innovation for vesicovaginal fistula repair.

Performance analysis of the transcatheter aortic valve implantation on blood flow hemodynamics: An optical imaging-based in vitro study.

Cardiac implants may have a strong influence on the hemodynamics of the circulatory system. In this study, we aimed at investigating the impact of transcatheter aortic valve implantation (TAVI) devices on blood flow patterns that develop in the ascending aorta under physiological flow conditions in vitro. For this purpose, a noninvasive optical measurement tool, three-dimensional particle tracking velocimetry (3D-PTV), was used in a realistic compliant silicone aortic model. The performance and the influence of two TAVIs and one surgical valve on the aortic flow were investigated. Our results showed that valve design and materials may have a distinct influence on relevant hemodynamic properties, namely kinetic energy, production of turbulence, and shear stresses in the ascending aorta. All properties varied considerably between the different valve models. We found that the total aortic regurgitation composed of the closing volume, transvalvular and paravalvular leakages varied for the three valves investigated. Furthermore, peak mean kinetic energy (MKE) ranged from 61 to 116 J/m3 , whereas peak turbulent kinetic energy (TKE) ranged from 23 to 36 J/m3 . The analysis of shear showed that all the three studied devices had minimal overall risk for thrombus formation. We conclude that the characteristics and material designs of TAVI devices have strong influences on the hemodynamics in the ascending aorta.

Rapidly Recoverable Thixotropic Hydrogels from the Racemate of Chiral OFm Monosubstituted Cyclo(Glu-Glu) Derivatives.

Both chiral OFm monosubstituted cyclo(l-Glu-l-Glu) and cyclo(d-Glu-d-Glu) display a robust gelation ability in a variety of organic solvents and water. In contrast to an individual enantiomer, their racemate can form rapidly recoverable thixotropic hydrogels with a remarkably shorter thixotropic recovery time. This unexpected thixotropic behavior is induced by the random arrangement of d- and l-enantiomers in the cell units, leading to the formation of "pseudoracemate", noncrystalline self-assemblies in the resulting 3D fibrous network.

Analysis of morphological properties of fibrous electrospun polyurethane grafts using image segmentation.

The concentration of the polymer in the electrospinning solution greatly influences the mechanical behaviour of electrospun vascular grafts due to the influence on scaffold morphology. The scaffold morphology (fiber diameter, fiber orientation and inter-fiber voids) of the grafts plays an important role in their behaviour during use. Even though manual methods and complex algorithms have been used so far for characterisation of the morphology of electrospun architecture, they still have several drawbacks that limit their reliability. This study therefore uses conventional, statistical region merging and a hybrid image segmentation algorithm, to characterise the morphology of the electrospun vascular grafts. Consequently, vascular grafts were fabricated using an in-house electrospinning equipment using three polymer material concentration levels (14%, 16% and 18%) of medical-grade thermoplastic polyurethane (Pellethane®). The image thresholding and segementation algorithms were then used for segmentation of SEM images extracted from the polymer grafts and then morphological parameters were investigated in terms of fiber diameter, fiber orientation, and interfiber spaces (pore area and porosity). The results indicate that electrospun image segmentation was "best" when the hybrid algorithm and the conventional algorithm was used, which implied that fiber property values computed from the hybrid algorithm were closed to the manually measurements especially for the 14% PU with fiber diameter 2.2%, fiber orientation 7.6% and porosity at 1.9%. However there was higher disperity between the manual and hybrid algorithm. This suggests more fiber uniformity in the 14%PU potentially affected the accuracy of the hybrid algorithm.

Differentiating transmural from transanastomotic prosthetic graft endothelialization through an isolation loop-graft model.

BACKGROUND: In humans, transanastomotic endothelial outgrowth onto the surface of prosthetic vascular grafts is limited to the immediate perianastomotic region, even after years of implantation. In contrast, continual transanastomotic outgrowth together with short graft lengths has led to early endothelial confluence in most animal models pre-empting endothelialization through transmural capillary sprouting. We describe an isolation loop-graft model that clearly separates these distinctly different events. METHODS: Baseline transanastomotic endothelialization was assessed by implanting low-porosity expanded polytetrafluoroethylene grafts (ePTFE; internal diameter 1.7 mm; internodal distance 15-25 µm; 14.2 ± 1.6 mm long) for 2, 4, and 6 weeks (n = 6/time point) in the abdominal aorta of Wistar rats. High-porosity polyurethane (internal diameter 1.7 mm-150 µm pore size) grafts were then interposed ("welded") into the midsection of the ePTFE grafts for 2, 4, 6, and 8 weeks (n = 6/time point). Looping the interposition grafts increased their length to 70.3 ± 8.3 mm. After implantation periods of 6, 8, 12, and 24 weeks (n = 8/time point) isolation loop grafts were analyzed by light, immune-fluorescence (CD31) and scanning electron microscopy, and endothelialization was expressed as maximal transanastomotic endothelial outgrowth (I(max)), mean transanastomotic outgrowth (I(mean)), and segmental graft coverage (GSE). RESULTS: Transanastomotic outgrowth slowed down between 2 and 6 weeks of implantation (proximal: [I(max) from 0.9 ± 0.5 to 0.3 ± 0.3 mm/wk; P < .04; I(mean) from 0.3 ± 0.1 to 0.2 ± 0.1 mm/wk; nonsignificant (NS)]; distal: [I(max) from 0.7 ± 0.3 to 0.3 ± 0.2 mm/wk; P < .02; I(mean) from 0.3 ± 0.2 to 0.2 ± 0.0 mm/wk; NS]) but remained constant thereafter (I(max) = 0.5 ± 0.2 mm/wk; I(mean) = 0.4 ± 0.2 mm/wk at 24 weeks NS). In straight composite grafts, the ePTFE separation zones were too short to isolate transmural ingrowth beyond week 4. In contrast, a broad endothelial-free separation zone was preserved in all looped composite grafts even after half a year of implantation (25.9 ± 5.9 vs 8.7 ± 4.9 mm proximally and 21.9 ± 13.4 vs 12.3 ± 6.2 mm distally at 6 and 24 weeks, respectively). Ninety-three percent of patent loop-grafts showed isolated transmural midgraft endothelium after 4 weeks and 97% after 6 weeks. Midgraft preconfluence was reached by 6 weeks (GSE = 55 ± 45%) and confluence between week 12 and 24 (GSE = 95.0 ± 10.0% and 84.0 ± 30.13%). The subintimal thickness stayed constant with a nonsignificant trend toward regression (91.8 ± 93.9 mm vs 71.4 ± 59.4 mm at 6 and 24 weeks, respectively; NS). CONCLUSIONS: Transmural endothelialization can be clearly distinguished from transanastomotic outgrowth in a high throughput rat model. A looped interposition graft model provides sufficient isolation length to separate the two events for up to half a year and does not result in an increase in intimal hyperplasia. CLINICAL RELEVANCE: Although the mode of graft deployment has changed over the years, the problem of an absent surface endothelium remains, whether small- to medium-diameter grafts are surgically implanted or placed endovascularly as "covered stents." In contrast to humans, most animal models experience progressive transanastomotic endothelial outgrowth. Together with graft lengths that were too short, the clinically irrelevant transanastomotic endothelialization inadvertently led to early endothelial confluence in the vast majority of experimental vascular graft studies pre-empting or concealing alternative modes of endothelialization. The isolation loop-graft model we propose allows the long-term differentiation of the different modes of endothelialization in a small animal screening model.

Mechanical reinforcement of amniotic membranes for vesicovaginal fistula repair.

INTRODUCTION: Amniotic membranes (AM) have shown its great potential in reconstructive surgery due to their regenerative capacity. However, AM is regarded to be relatively weak when applied for load-bearing purposes. This study aims to produce an AM-based scaffold that can withstand the mechanical loads applied in vesicovaginal fistula repair. Different strategies are investigated to improve the mechanical characteristics of AM. METHODS: Single and multilayered AM, and composite constructs of AM with electrospun poly-4-hydroxybutyrate (P4HB) or bovine pericardial tissue combined with the use of fibrin glue, were mechanically tested in this study. Suture retention strength and mechanical characteristics (tensile stress, elongation, tangent modulus and maximum load) were assessed by uniaxial testing. The effect of degradation of the composite constructs on the mechanical characteristics was determined by uniaxial testing after 4 and 8 weeks. RESULTS: Single and multilayered AM could not provide the mechanical requirements needed for surgical implantation (>2N load). AM was combined successfully with electrospun P4HB and bovine pericardium with the use of fibrin glue and were able to exceed the 2N load. CONCLUSION: The composite constructs with AM showed sufficient mechanical characteristics for surgical implantation. Electrospun P4HB combined with AM seemed the most promising candidate since the mechanical characteristics of P4HB can be further modified to meet the requirements of the application site and the degradation of the P4HB allows a gradual transfer of load. Eventhough the scaffold is intended for fistula repair, it can potentially be applied in surgical reconstruction of other hollow organs by modifying the mechanical characteristics.

Vaginal changes after ovariectomy in ewes: A large animal model for genitourinary syndrome of menopause.

OBJECTIVE: To evaluate the effect of iatrogenic menopause on the physiology of the vagina of the ewe and to evaluate if vaginal changes in ewes can be translated to women with genitourinary syndrome of menopause (GSM). METHODS: Preclinical research with Dohne Merino ewes. Iatrogenic menopause was induced by bilateral ovariectomy (OVX). Animals were randomized for surgery, blinded for allocation and outcome assessment. Differences between groups were determined by linear regression analyses at 5 months after OVX. Outcome measures were vaginal epithelial thickness, pH, vaginal maturation value, vaginal maturation index, epithelial glycogen accumulation, content of elastin fibers, collagen, and vascularity. RESULTS: OVX ewes (n = 20) showed epithelial thinning of the vaginal wall from 146 µm to 47 µm (mean, P < 0.001). Furthermore, epithelial glycogen accumulation and vascularity of the vaginal wall significantly decreased (43% and 23%, respectively) as compared with the control group (no intervention; n = 5). No significant differences were found for other outcome measures. CONCLUSION: This study established the ewe as a suitable large animal model for GSM. Furthermore, the similar relevant outcomes in humans and ewes hold great value for future translational research for the evaluation and optimization of different treatment modalities for GSM.

Efficacy, safety, and palatability of arpraziquantel (L-praziquantel) orodispersible tablets in children aged 3 months to 6 years infected with Schistosoma in Côte d'Ivoire and Kenya: an open-label, partly randomised, phase 3 trial.

BACKGROUND: WHO has underlined the need for a child-friendly treatment for schistosomiasis, a prevalent parasitic disease in low-income and middle-income countries. After successful phase 1 and 2 trials, we aimed to evaluate the efficacy, safety, palatability, and pharmacokinetics of arpraziquantel (L-praziquantel) orodispersible tablets for preschool-aged children. METHODS: This open-label, partly randomised, phase 3 study was conducted at two hospitals in Côte d'Ivoire and Kenya. Children with a minimum bodyweight of 5 kg in those aged 3 months to 2 years and 8 kg in those aged 2-6 years were eligible. In cohort 1, participants aged 4-6 years infected with Schistosoma mansoni were randomly assigned (2:1) to receive a single dose of oral arpraziquantel 50 mg/kg (cohort 1a) or oral praziquantel 40 mg/kg (cohort 1b) using a computer-generated randomisation list. Cohorts 2 (aged 2-3 years) and 3 (aged 3 months to 2 years) infected with S mansoni, and the first 30 participants in cohort 4a (aged 3 months to 6 years) infected with Schistosoma haematobium, received a single dose of oral arpraziquantel 50 mg/kg. After follow-up assessments, arpraziquantel was increased to 60 mg/kg (cohort 4b). Laboratory personnel were masked to the treatment group, screening, and baseline values. S mansoni was detected using a point-of-care circulating cathodic antigen urine cassette test and confirmed using the Kato-Katz method. The primary efficacy endpoint was clinical cure rate at 17-21 days after treatment in cohorts 1a and 1b, measured in the modified intention-to-treat population and calculated using the Clopper-Pearson method. This study is registered with ClinicalTrials.gov, NCT03845140. FINDINGS: Between Sept 2, 2019, and Aug 7, 2021, 2663 participants were prescreened and 326 were diagnosed with S mansoni or S haematobium. 288 were enrolled (n=100 in cohort 1a, n=50 in cohort 1b, n=30 in cohort 2, n=18 in cohort 3, n=30 in cohort 4a, and n=60 in cohort 4b), but eight participants received antimalarial drugs and were excluded from the efficacy analyses. The median age was 5·1 years (IQR 4·1-6·0) and 132 (47%) of 280 participants were female and 148 (53%) were male. Cure rates with arpraziquantel were similar to those with praziquantel (87·8% [95% CI 79·6-93·5] in cohort 1a vs 81·3% [67·4-91·1] in cohort 1b). No safety concerns were identified during the study. The most common drug-related treatment-emergent adverse events were abdominal pain (41 [14%] of 288 participants), diarrhoea (27 [9%]), vomiting (16 [6%]), and somnolence (21 [7%]). INTERPRETATION: Arpraziquantel, a first-line orodispersible tablet, showed high efficacy and favourable safety in preschool-aged children with schistosomiasis. FUNDING: The Global Health Innovative Technology Fund, the European and Developing Countries Clinical Trials Partnership, and the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945).

Causal chemoprophylactic activity of cabamiquine against Plasmodium falciparum in a controlled human malaria infection: a randomised, double-blind, placebo-controlled study in the Netherlands.

BACKGROUND: Cabamiquine is a novel antimalarial that inhibits Plasmodium falciparum translation elongation factor 2. We investigated the causal chemoprophylactic activity and dose-exposure-response relationship of single oral doses of cabamiquine following the direct venous inoculation (DVI) of P falciparum sporozoites in malaria-naive, healthy volunteers. METHODS: This was a phase 1b, randomised, double-blind, placebo-controlled, adaptive, dose-finding, single-centre study performed in Leiden, Netherlands. Malaria-naive, healthy adults aged 18-45 years were divided into five cohorts and randomly assigned (3:1) to receive cabamiquine or placebo. Randomisation was done by an independent statistician using codes in a permuted block schedule with a block size of four. Participants, investigators, and study personnel were masked to treatment allocation. A single, oral dose regimen of cabamiquine (200, 100, 80, 60, or 30 mg) or matching placebo was administered either at 2 h (early liver-stage) or 96 h (late liver-stage) after DVI. The primary endpoints based on a per-protocol analysis set were the number of participants who developed parasitaemia within 28 days of DVI, time to parasitaemia, number of participants with documented parasite blood-stage growth, clinical symptoms of malaria, and exposure-efficacy modelling. The impact of cabamiquine on liver stages was evaluated indirectly by the appearance of parasitaemia in the blood. The Clopper-Pearson CI (nominal 95%) was used to express the protection rate. The secondary outcomes were safety and tolerability, assessed in those who had received DVI and were administered one dose of the study intervention. The trial was prospectively registered on ClinicalTrials.gov (NCT04250363). FINDINGS: Between Feb 17, 2020 and April 29, 2021, 39 healthy participants were enrolled (early liver-stage: 30 mg [n=3], 60 mg [n=6], 80 mg [n=6], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=6]; late liver-stage: 60 mg [n=3], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=3]). A dose-dependent causal chemoprophylactic effect was observed, with four (67%) of six participants in the 60 mg, five (83%) of six participants in the 80 mg, and all three participants in the 100 and 200 mg cabamiquine dose groups protected from parasitaemia up to study day 28, whereas all participants in the pooled placebo and 30 mg cabamiquine dose group developed parasitaemia. A single, oral dose of 100 mg cabamiquine or higher provided 100% protection against parasitaemia when administered during early or late liver-stage malaria. The median time to parasitaemia in those with early liver-stage malaria was prolonged to 15, 22, and 24 days for the 30, 60, and 80 mg dose of cabamiquine, respectively, compared with 10 days for the pooled placebo. All participants with positive parasitaemia showed documented blood-stage parasite growth, apart from one participant in the pooled placebo group and one participant in the 30 mg cabamiquine group. Most participants did not exhibit any malaria symptoms in both the early and late liver-stage groups, and those reported were mild in severity. A positive dose-exposure-efficacy relationship was established across exposure metrics. The median maximum concentration time was 1-6 h, with a secondary peak observed between 6 h and 12 h in all cabamiquine dose groups (early liver-stage). All cabamiquine doses were safe and well tolerated. Overall, 26 (96%) of 27 participants in the early liver-stage group and ten (83·3%) of 12 participants in the late liver-stage group reported at least one treatment-emergent adverse event (TEAE) with cabamiquine or placebo. Most TEAEs were of mild severity, transient, and resolved without sequelae. The most frequently reported cabamiquine-related TEAE was headache. No dose-related trends were observed in the incidence, severity, or causality of TEAEs. INTERPRETATION: The results from this study show that cabamiquine has a dose-dependent causal chemoprophylactic activity. Together with previously demonstrated activity against the blood stages combined with a half-life of more than 150 h, these results indicate that cabamiquine could be developed as a single-dose monthly regimen for malaria prevention. FUNDING: The healthcare business of Merck KGaA, Darmstadt, Germany.

Absorbable Electrospun Poly-4-hydroxybutyrate Scaffolds as a Potential Solution for Pelvic Organ Prolapse Surgery.

Women with pelvic organ prolapse (POP) have bothersome complaints that significantly affect their quality of life. While native tissue repair is associated with high recurrence rates, polypropylene knitted implants have caused specific implant-related adverse events that have detrimental, often irreversible, effects. We hypothesize that surgical outcome can be improved with a tissue-engineered solution using an absorbable implant that mimics the natural extracellular matrix (ECM) structure, releases estrogen, and activates collagen metabolism by fibroblasts as the main regulators of wound healing. To this aim, we produced electrospun poly-4-hydroxybutyrate (P4HB) scaffolds and biofunctionalized them with estradiol (E2). The cell-implant interactions relevant for POP repair were assessed by seeding primary POP vaginal fibroblasts isolated from patients on electrospun P4HB scaffolds with 1%, 2%, or 5% E2 and without E2. To test our hypothesis on whether ECM mimicking structures should improve regeneration, electrospun P4HB was compared to knitted P4HB implants. We evaluated vaginal fibroblast proliferation, ECM deposition, and metabolism by quantification of collagen, elastin, and matrix metalloproteinases and by gene expression analysis for 28 days. We established effective E2 drug loading with a steady release over time. Significantly higher cell proliferation, collagen-, and elastin deposition were observed on electrospun P4HB scaffolds as compared to knitted P4HB. For this study, physical properties of the scaffolds were more determinant on the cell response than the release of E2. These results indicate that making these electrospun P4HB scaffolds E2-releasing appears to be technically feasible. In addition, electrospun P4HB scaffolds promote the cellular response of vaginal fibroblasts and further studies are merited to assess if their use results in improved surgical outcomes in case of POP repair.

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets.

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors. Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds. 3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 ± 1.6 µm. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5. With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.

The Technological Basis of a Balloon-Expandable TAVR System: Non-occlusive Deployment, Anchorage in the Absence of Calcification and Polymer Leaflets.

Leaflet durability and costs restrict contemporary trans-catheter aortic valve replacement (TAVR) largely to elderly patients in affluent countries. TAVR that are easily deployable, avoid secondary procedures and are also suitable for younger patients and non-calcific aortic regurgitation (AR) would significantly expand their global reach. Recognizing the reduced need for post-implantation pacemakers in balloon-expandable (BE) TAVR and the recent advances with potentially superior leaflet materials, a trans-catheter BE-system was developed that allows tactile, non-occlusive deployment without rapid pacing, direct attachment of both bioprosthetic and polymer leaflets onto a shape-stabilized scallop and anchorage achieved by plastic deformation even in the absence of calcification. Three sizes were developed from nickel-cobalt-chromium MP35N alloy tubes: Small/23 mm, Medium/26 mm and Large/29 mm. Crimp-diameters of valves with both bioprosthetic (sandwich-crosslinked decellularized pericardium) and polymer leaflets (triblock polyurethane combining siloxane and carbonate segments) match those of modern clinically used BE TAVR. Balloon expansion favors the wing-structures of the stent thereby creating supra-annular anchors whose diameter exceeds the outer diameter at the waist level by a quarter. In the pulse duplicator, polymer and bioprosthetic TAVR showed equivalent fluid dynamics with excellent EOA, pressure gradients and regurgitation volumes. Post-deployment fatigue resistance surpassed ISO requirements. The radial force of the helical deployment balloon at different filling pressures resulted in a fully developed anchorage profile of the valves from two thirds of their maximum deployment diameter onwards. By combining a unique balloon-expandable TAVR system that also caters for non-calcific AR with polymer leaflets, a powerful, potentially disruptive technology for heart valve disease has been incorporated into a TAVR that addresses global needs. While fulfilling key prerequisites for expanding the scope of TAVR to the vast number of patients of low- to middle income countries living with rheumatic heart disease the system may eventually also bring hope to patients of high-income countries presently excluded from TAVR for being too young.

Knitted nitinol represents a new generation of constrictive external vein graft meshes.

OBJECTIVE: Constriction of vein grafts with braided external nitinol meshes had previously led to the successful elimination of neointimal tissue formation. We investigated whether pulse compliance, smaller kink-free bending radius, and milder medial atrophy can be achieved by knitting the meshes rather than braiding, without losing the suppressive effect on intimal hyperplasia. METHODS: Pulse compliance, bending stiffness, and bending radius, as well as longitudinal-radial deformation-coupling and radial compression, were compared in braided and knitted nitinol meshes. Identical to previous studies with braided mesh grafts, a senescent nonhuman primate model (Chacma baboons; bilateral femoral interposition grafts/6 months) mimicking the clinical size mismatch between vein grafts and runoff arteries was used to examine the effect of knitted external meshes on vein grafts: nitinol mesh-constricted (group 1); nitinol mesh-constricted and fibrin sealant (FS) spray-coated for mesh attachment (group 2); untreated control veins (group 3), and FS spray-coated control veins (group 4). RESULTS: Compared with braided meshes, knitted meshes had 3.8-times higher pulse compliance (3.43 ± 0.53 vs 0.94 ± 0.12%/100 mm Hg; P = .00002); 30-times lower bending stiffness (0.015 ± 0.002 vs 0.462 ± 0.077 Nmm(2); P = .0006); 9.2-times narrower kink-free bending radius (15.3 ± 0.4 vs 140.8 ± 22.4 mm; P = .0006), and 4.3-times lower radial narrowing caused by axial distension (18.0% ± 1.0% vs 77.0% ± 3.7%; P = .00001). Compared with mesh-supported grafts, neointimal tissue was 8.5-times thicker in group I (195 ± 45 µm) vs group III (23.0 ± 21.0 µm; P < .001) corresponding with a 14.3-times larger neointimal area in group I (4330 ± 957 × 103 µm(2)) vs group III (303 ± 221× 103 µm(2); P < .00004). FS had no significant influence. Medial muscle mass remained at 43.4% in knitted meshes vs the 28.1% previously observed in braided meshes. CONCLUSION: Combining the suppression of intimal hyperplasia with a more physiologic remodeling process of the media, manifold higher kink-resistance, and lower fraying than in braided meshes makes knitted nitinol an attractive concept in external vein graft protection.

Residual Bioprosthetic Valve Immunogenicity: Forgotten, Not Lost.

Despite early realization of the need to control inherent immunogenicity of bioprosthetic replacement heart valves and thereby mitigate the ensuing host response and its associated pathology, including dystrophic calcification, the problem remains unresolved to this day. Concerns over mechanical stiffness associated with prerequisite high cross-link density to effect abrogation of this response, together with the insinuated role of leaching glutaraldehyde monomer in subsequent dystrophic mineralization, have understandably introduced compromises. These have become so entrenched as a benchmark standard that residual immunogenicity of the extracellular matrix has seemingly been relegated to a very subordinate role. Instead, focus has shifted toward the removal of cellular compartment antigens renowned for their implication in the failure of vascularized organ xenotransplants. While decellularization certainly offers advantages, this review aims to refocus attention on the unresolved matter of the host response to the extracellular matrix. Furthermore, by implicating remnant immune and inflammatory processes to bioprosthetic valve pathology, including pannus overgrowth and mineralization, the validity of a preeminent focus on decellularization, in the context of inefficient antigen and possible residual microbial remnant removal, is questioned.

Long-Term Stability and Biocompatibility of Pericardial Bioprosthetic Heart Valves.

The use of bioprostheses for heart valve therapy has gradually evolved over several decades and both surgical and transcatheter devices are now highly successful. The rapid expansion of the transcatheter concept has clearly placed a significant onus on the need for improved production methods, particularly the pre-treatment of bovine pericardium. Two of the difficulties associated with the biocompatibility of bioprosthetic valves are the possibilities of immune responses and calcification, which have led to either catastrophic failure or slow dystrophic changes. These have been addressed by evolutionary trends in cross-linking and decellularization techniques and, over the last two decades, the improvements have resulted in somewhat greater durability. However, as the need to consider the use of bioprosthetic valves in younger patients has become an important clinical and sociological issue, the requirement for even greater longevity and safety is now paramount. This is especially true with respect to potential therapies for young people who are afflicted by rheumatic heart disease, mostly in low- to middle-income countries, for whom no clinically acceptable and cost-effective treatments currently exist. To extend longevity to this new level, it has been necessary to evaluate the mechanisms of pericardium biocompatibility, with special emphasis on the interplay between cross-linking, decellularization and anti-immunogenicity processes. These mechanisms are reviewed in this paper. On the basis of a better understanding of these mechanisms, a few alternative treatment protocols have been developed in the last few years. The most promising protocol here is based on a carefully designed combination of phases of tissue-protective decellularization with a finely-titrated cross-linking sequence. Such refined protocols offer considerable potential in the progress toward superior longevity of pericardial heart valves and introduce a scientific dimension beyond the largely disappointing 'anti-calcification' treatments of past decades.

Tendon-like tether formation for tongue-base advancement in an ovine model using a novel implant device intended for the surgical management of obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is a serious debilitating condition with significant morbidity and mortality affecting almost one billion adults globally. The current gold standard in the non-surgical management of airway collapse is continuous positive airway pressure (CPAP). However, non-compliance leads to a high abandon rate (27-46%). While there are multiple sites of airway obstruction during sleep, the tongue base is recognized as the key player in the pathogenesis of OSA. Poor outcomes of current tongue suspension devices are due to fracture, slippage or migration of devices. Three tongue tethering device groups, namely a polydioxanone/polyurethane combination (PDO + PU) treatment group, a PDO analytical control group, and a polypropylene (PP) descriptive control group, were implanted into 22 sheep (75-85 kg) in a two-phased study. After implant times of 8, 16, and 32 weeks, sheep were serially euthanized to allow for explantation of their tongues and chins. The PDO + PU devices remodeled during the 32-week implant period into a hybrid biological tendon-like tether through the process of gradual degradation of the PDO and collagen deposition as shown by electrophoresis, histology and mechanical testing. The control PDO device degraded completely after 32 weeks and the PP devices remained intact. The hybrid biological tendon-like tether exhibited a break-strength of 60 N, thus exceeding the maximum force to overcome upper airway collapse.

Comparative palatability of orally disintegrating tablets (ODTs) of Praziquantel (L-PZQ and Rac-PZQ) versus current PZQ tablet in African children: A randomized, single-blind, crossover study.

BACKGROUND: Praziquantel (PZQ) is currently the only recommended drug for infection and disease caused by the schistosome species that infects humans; however, the current tablet formulation is not suitable for pre-school age children mainly due to its bitterness and the large tablet size. We assessed the palatability of two new orally disintegrating tablet (ODT) formulations of PZQ. METHODOLOGY: This randomized, single-blind, crossover, swill-and-spit palatability study (NCT02315352) was carried out at a single school in Tanzania in children aged 6-11 years old, with or without schistosomiasis infection as this was not part of the assessment. Children were stratified according to age group (6-8 years or 9-11 years) and gender, then randomized to receive each formulation in a pre-specified sequence. Over 2 days, the children assessed the palatability of Levo-Praziquantel (L-PZQ) ODT 150 mg and Racemate Praziquantel (Rac-PZQ) ODT 150 mg disintegrated in the mouth without water on the first day, and L-PZQ and Rac-PZQ dispersed in water and the currently available PZQ 600 mg formulation (PZQ-Cesol) crushed and dispersed in water on the second day. The palatability of each formulation was rated using a 100 mm visual analogue scale (VAS) incorporating a 5-point hedonic scale, immediately after spitting out the test product (VASt = 0 primary outcome) and after 2-5 minutes (VASt = 2-5). PRINCIPAL FINDINGS: In total, 48 children took part in the assessment. Overall, there was no reported difference in the VASt = 0 between the two ODT formulations (p = 0.106) without water. Higher VASt = 0 and VASt = 2-5 scores were reported for L-PZQ ODT compared with Rac-PZQ ODT in older children (p = 0.046 and p = 0.026, respectively). The VASt = 0 and VASt = 2-5 were higher for both ODT formulations compared with the standard formulation (p<0.001 for both time points). No serious adverse events were reported. CONCLUSIONS/SIGNIFICANCE: The new paediatric-friendly formulations dispersed in water were both found to be more palatable than the existing standard formulation of PZQ. There may be gender and age effects on the assessment of palatability. Further research is needed for assessing efficacy and tolerability of the newly ODTs Praziquantel drug in younger children. TRIAL REGISTRATION: The trial was registered on ClinicalTrials.gov (NCT02315352) and in the Pan African Clinical Trials Registry (PACTR201412000959159).

Analysis of the regenerative capacity of human serum exosomes after a simple multistep separation from lipoproteins.

Due to the abundance of lipoproteins in blood, it is challenging to characterize the biological functions and components of blood-derived extracellular vesicles. The aim of this study was to develop a multiple-step purification protocol to separate serum exosomes from serum proteins and lipoproteins and assess their regenerative potential. Exosomes were isolated by concentrating them in human serum using ultracentrifugation (UC), followed sequentially by density gradient (DG) UC and size exclusion chromatography (SEC). Purity and characterization were assessed by western blots, Lipoprint®, enzyme-linked immunosorbent assay, electron microscopy, mass spectrometry, and nanoparticle tracking analysis. Functionality was assessed by cell proliferation analysis and with an in vivo subcutaneous angiogenesis model. SEC alone isolated nano-sized vesicles possessing vesicle markers TSG101 and CD9, but there was a substantial presence of apolipoprotein B, predominantly derived from very-low- and intermediate-density lipoprotein particles. This was reduced to an undetectable level using the combined UC DG SEC approach. Mass spectrometry identified 224 proteins in UC DG SEC isolates relative to the 135 from SEC, with considerable increases in exosome-related proteins and reductions in lipoproteins. A consistent but limited increase in human dermal fibroblast proliferation and evidence of neovascularization enhancement were observed after exposure to UC DG SEC exosomes. An UC DG SEC purification protocol considerably improved the removal of lipoproteins during isolation of serum exosomes. The purified exosomes stimulated cell proliferation and potentially increased an in vivo angiogenic response. This multistep purification allows for more accurate identification of serum exosome functional activity and composition.

Safety, pharmacokinetics, and antimalarial activity of the novel plasmodium eukaryotic translation elongation factor 2 inhibitor M5717: a first-in-human, randomised, placebo-controlled, double-blind, single ascending dose study and volunteer infection study.

BACKGROUND: M5717 is the first plasmodium translation elongation factor 2 inhibitor to reach clinical development as an antimalarial. We aimed to characterise the safety, pharmacokinetics, and antimalarial activity of M5717 in healthy volunteers. METHODS: This first-in-human study was a two-part, single-centre clinical trial done in Brisbane, QLD, Australia. Part one was a double-blind, randomised, placebo-controlled, single ascending dose study in which participants were enrolled into one of nine dose cohorts (50, 100, 200, 400, 600, 1000, 1250, 1800, or 2100 mg) and randomly assigned (3:1) to M5717 or placebo. A sentinel dosing strategy was used for each dose cohort whereby two participants (one assigned to M5717 and one assigned to placebo) were initially randomised and dosed. Randomisation schedules were generated electronically by independent, unblinded statisticians. Part two was an open-label, non-randomised volunteer infection study using the Plasmodium falciparum induced blood-stage malaria model in which participants were enrolled into three dose cohorts. Healthy men and women of non-childbearing potential aged 18-55 years were eligible for inclusion; individuals in the volunteer infection study were required to be malaria naive. Safety and tolerability (primary outcome of the single ascending dose study and secondary outcome of the volunteer infection study) were assessed by frequency and severity of adverse events. The pharmacokinetic profile of M5717 was also characterised (primary outcome of the volunteer infection study and secondary outcome of the single ascending dose study). Parasite clearance kinetics (primary outcome of the volunteer infection study) were assessed by the parasite reduction ratio and the corresponding parasite clearance half-life; the incidence of recrudescence up to day 28 was determined (secondary outcome of the volunteer infection study). Recrudescent parasites were tested for genetic mutations (exploratory outcome). The trial is registered with ClinicalTrials.gov (NCT03261401). FINDINGS: Between Aug 28, 2017, and June 14, 2019, 221 individuals were assessed for eligibility, of whom 66 men were enrolled in the single ascending dose study (eight per cohort for 50-1800 mg cohorts, randomised three M5717 to one placebo, and two in the 2100 mg cohort, randomised one M5717 to one placebo) and 22 men were enrolled in the volunteer infection study (six in the 150 mg cohort and eight each in the 400 mg and 800 mg cohorts). No adverse event was serious; all M5717-related adverse events were mild or moderate in severity and transient, with increased frequency observed at doses above 1250 mg. In the single ascending dose study, treatment-related adverse events occurred in three of 17 individuals in the placebo group; no individual in the 50 mg, 100 mg, or 200 mg groups; one of six individuals in each of the 400 mg, 1000 mg, and 1250 mg groups; two of six individuals in the 600 mg group; and in all individuals in the 1800 mg and 2100 mg groups. In the volunteer infection study, M5717-related adverse events occurred in no participants in the 150 mg or 800 mg groups and in one of eight participants in the 400 mg group. Transient oral hypoesthesia (in three participants) and blurred vision (in four participants) were observed in the 1800 mg or 2100 mg groups and constituted an unknown risk; thus, further dosing was suspended after dosing of the two sentinel individuals in the 2100 mg cohort. Maximum blood concentrations occurred 1-7 h after dosing, and a long half-life was observed (146-193 h at doses ≥200 mg). Parasite clearance occurred in all participants and was biphasic, characterised by initial slow clearance lasting 35-55 h (half-life 231·1 h [95% CI 40·9 to not reached] for 150 mg, 60·4 h [38·6 to 138·6] for 400 mg, and 24·7 h [20·4 to 31·3] for 800 mg), followed by rapid clearance (half-life 3·5 h [3·1 to 4·0] for 150 mg, 3·9 h [3·3 to 4·8] for 400 mg, and 5·5 h [4·8 to 6·4] for 800 mg). Recrudescence occurred in three (50%) of six individuals dosed with 150 mg and two (25%) of eight individuals dosed with 400 mg. Genetic mutations associated with resistance were detected in four cases of parasite recrudescence (two individuals dosed with 150 mg and two dosed with 400 mg). INTERPRETATION: The safety, pharmacokinetics, and antimalarial activity of M5717 support its development as a component of a single-dose antimalarial combination therapy or for malaria prophylaxis. FUNDING: Wellcome Trust and the healthcare business of Merck KGaA, Darmstadt, Germany.