Full-field strain distribution in hierarchical electrospun nanofibrous poly-L(lactic) acid/collagen scaffolds for tendon and ligament regeneration: A multiscale study

Regeneration of injured tendons and ligaments (T/L) is a worldwide need. In this study electrospun hierarchical scaffolds made of a poly-L (lactic) acid/collagen blend were developed reproducing all the multiscale levels of aggregation of these tissues. Scanning electron microscopy, microCT and tensile mechanical tests were carried out, including a multiscale digital volume correlation analysis to measure the full-field strain distribution of electrospun structures. The principal strains (εp1 and εp3) described the pattern of strains caused by the nanofibers rearrangement, while the deviatoric strains (εD) revealed the related internal sliding of nanofibers and bundles. The results of this study confirmed the biomimicry of such electrospun hierarchical scaffolds, paving the way to further tissue engineering and clinical applications.

Assessing frailty at the centers for dementia and cognitive decline in Italy: potential implications for improving care of older people living with dementia

INTRODUCTION

Frailty is strongly associated with the clinical course of cognitive impairment and dementia, thus arguing for the need of its assessment in individuals affected by cognitive deficits. This study aimed to retrospectively evaluate frailty in patients aged 65 years and older referred to two Centers for Cognitive Decline and Dementia (CCDDs).

METHODS

A total of 1256 patients consecutively referred for a first visit to two CCDDs in Lombardy (Italy) between January 2021 to July 2022 were included. All patients were evaluated by an expert physician in diagnosis and care of dementia according to a standardized clinical protocol. Frailty was assessed using a 24-items Frailty Index (FI) based on routinely collected health records, excluding cognitive decline or dementia, and categorized as mild, moderate, and severe.

RESULTS

Overall, 40% of patients were affected by mild frailty and 25% of the sample has moderate to severe frailty. The prevalence and severity of frailty increased with decreasing Mini Mental State Examination (MMSE) score and advancing age. Frailty was also detected in 60% of patients with mild cognitive impairment.

CONCLUSION

Frailty is common in patients referring to CCDDs for cognitive deficits. Its systematic assessment using a FI generated with readily available medical information could help develop appropriate models of assistance and guide personalization of care.

Self-Sensing Soft Skin Based on Piezoelectric Nanofibers

The development of electronic skins and wearable devices is rapidly growing due to their broad application fields, such as for biomedical, health monitoring, or robotic purposes. In particular, tactile sensors based on piezoelectric polymers, which feature self-powering capability, have been widely used thanks to their flexibility and light weight. Among these, poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) presents enhanced piezoelectric properties, especially if manufactured in a nanofiber shape. In this work, the enhanced piezoelectric performances of PVDF-TrFE nanofibers were exploited to manufacture a flexible sensor which can be used for wearable applications or e-skin. The piezoelectric signal was collected by carbon black (CB)-based electrodes, which were added to the active layer in a sandwich-like structure. The sensor was electromechanically characterized in a frequency range between 0.25 Hz and 20 Hz-which is consistent with human activities (i.e., gait cycle or accidental bumps)-showing a sensitivity of up to 4 mV/N. The parameters of the signal acquisition circuit were tuned to enable the sensor to work at the required frequency. The proposed electrical model of the nanofibrous piezoelectric sensor was validated by the experimental results. The sensitivity of the sensor remained above 77.5% of its original value after 10⁶ cycles of fatigue testing with a 1 kN compressive force.

Mental Health among Geriatric Healthcare Workers in Italy during the COVID-19 Pandemic: Results from a National Survey

OBJECTIVES

This study aimed to investigate the psychological impact of the COVID-19 pandemic on healthcare workers (HCWs) in geriatric settings.

DESIGN

Online cross-sectional survey.

SETTINGS AND PARTICIPANTS

394 geriatric HCWs in Italy.

MEASUREMENTS

The survey was developed by a multidisciplinary team and disseminated in April 2022 to the members of two geriatric scientific societies (Italian Society of Geriatrics and Gerontology and Italian Association of Psychogeriatrics). The survey examined the experiences related to the COVID-19 pandemic, as well as psychological burden and support. Work-related anxiety and distress related to the pandemic were studied using the SAVE-9 scale (Stress and Anxiety to Viral Epidemics).

RESULTS

Three hundred sixty-four participants (92.4%) changed their job activity during the pandemic and about half (50.9%) failed to cope with this change, 58 (14.7%) had increased work-related anxiety, and 39 (9.9%) work-related stress levels. Three hundred forty (86.3%) participants reported acute stress reaction symptoms, including irritability, depressed mood, headache, anxiety, and insomnia, and 262 (66.5%) required psychological support, mainly from friends/relatives (57.9%) and/or colleagues (32.5%). Furthermore, 342 participants (86.8%) recognized they would benefit from informal and formal psychological support in case of future similar emergencies.

CONCLUSIONS

This study highlights the high psychological burden experienced by geriatric HCWs in Italy during the COVID-19 pandemic and emphasizes the need for supportive interventions.

Is Graphene Always Effective in Reinforcing Composites? The Case of Highly Graphene-Modified Thermoplastic Nanofibers and Their Unfortunate Application in CFRP Laminates

Graphene (G) can effectively enhance polymers' and polymer composites' electric, thermal, and mechanical properties. Nanofibrous mats have been demonstrated to significantly increase the interlaminar fracture toughness of composite laminates, hindering delamination and, consequently, making such materials safer and more sustainable thanks to increased service life. In the present paper, poly(ethylene oxide) (PEO), polycaprolactone (PCL), and Nylon 66 nanofibers, plain or reinforced with G, were integrated into epoxy-matrix Carbon Fiber Reinforced Polymers (CFRPs) to evaluate the effect of polymers and polymers + G on the laminate mechanical properties. The main aim of this work is to compare the reinforcing action of the different nanofibers (polyether, polyester, and polyamide) and to disclose the effect of G addition. The polymers were chosen considering their thermal properties and, consequently, their mechanism of action against delamination. PEO and PCL, displaying a low melting temperature, melt, and mix during the curing cycle, act via matrix toughening; in this context, they are also used as tools to deploy G specifically in the interlaminar region when melting and mixing with epoxy resin. The high extent of modification stems from an attempt to deploy it in the interlaminar layer, thus diluting further in the resin. In contrast, Nylon 66 does not melt and maintain the nanostructure, allowing laminate toughening via nanofiber bridging. The flexural properties of the nanomodifed CFRPs were determined via a three-point bending (3PB) test, while delamination behavior in Mode I and Mode II was carried out using Double Cantilever Beam (DCB) and End-Notched Flexture (ENF) tests, respectively. The lack of a positive contribution of G in this context is an interesting point to raise in the field of nanoreinforced CFRP.

Rubber-enhanced polyamide nanofibers for a significant improvement of CFRP interlaminar fracture toughness

Nanofibrous mats provide substantial delamination hindering in composite laminates, especially if the polymer (as rubbers) can directly toughen the composite resin. Here, the well-known Nylon 66 nanofibers were impregnated with Nitrile Butadiene Rubber (NBR) for producing rubber/thermoplastic membranes for hampering the delamination of epoxy Carbon Fiber Reinforced Polymers (CFRPs). The starting polyamide mats were electrospun using two different solvent systems, and their effect on the mat's thermal and mechanical properties was investigated, as well as the laminate Mode I delamination resistance via Double Cantilever Beam (DCB) tests. Plain Nylon 66 mats electrospun from formic acid/chloroform perform better than the ones obtained from a solvent system containing trifluoroacetic acid, showing up to + 64% vs + 53% in interlaminar fracture toughness (G_I), respectively. The effect of NBR coating benefits both nanofiber types, significantly raising the G_I. The best results are obtained when interleaving medium-thickness and lightweight mats (20 µm, 9-10 g/m²) with 70-80 wt% of loaded rubber, achieving up to + 180% in G_I. The work demonstrates the ability of NBR at improving the delamination hindering of common polyamide nonwovens, paving the way to the use of NBR-coated Nylon 66 nanofibers as effective interleaves for G_I enhancement and overall composite safety improvement.

New Application Field of Polyethylene Oxide: PEO Nanofibers as Epoxy Toughener for Effective CFRP Delamination Resistance Improvement

Delamination is the most severe weakness affecting all composite materials with a laminar structure. Nanofibrous mat interleaving is a smart way to increase the interlaminar fracture toughness: the use of thermoplastic polymers, such as poly(ε-caprolactone) and polyamides (Nylons), as nonwovens is common and well established. Here, electrospun polyethylene oxide (PEO) nanofibers are proposed as reinforcing layers for hindering delamination in epoxy-based carbon fiber-reinforced polymer (CFRP) laminates. While PEO nanofibers are well known and successfully applied in medicine and healthcare, to date, their use as composite tougheners is undiscovered, resulting in the first investigation in this application field. The PEO-modified CFRP laminate shows a significant improvement in the interlaminar fracture toughness under Mode I loading: +60% and +221% in G _I,C and G _I,R, respectively. The high matrix toughening is confirmed by the crack path analysis, showing multiple crack planes, and by the delamination surfaces, revealing that extensive phase separation phenomena occur. Under Mode II loading, the G _II enhancement is almost 20%. Despite a widespread phase separation occurring upon composite curing, washings in water do not affect the surface delamination morphology, suggesting a sufficient humidity resistance of the PEO-modified laminate. Moreover, it almost maintains both the original stiffness and glass transition temperature (T _g), as assessed via three-point bending and dynamic mechanical analysis tests. The achieved results pave the way for using PEO nanofibrous membranes as a new effective solution for hindering delamination in epoxy-based composite laminates.

Self-Assembled NBR/Nomex Nanofibers as Lightweight Rubbery Nonwovens for Hindering Delamination in Epoxy CFRPs

Still today, concerns regarding delamination limit the widespread use of high-performance composite laminates, such as carbon fiber-reinforced polymers (CFRPs), to replace metals. Nanofibrous mat interleaving is a well-established approach to reduce delamination. However, nanomodifications may strongly affect other laminate thermomechanical properties, especially if achieved by integrating soft materials. Here, this limitation is entirely avoided by using rubbery nitrile butadiene rubber (NBR)/Nomex mixed nanofibers: neither laminate stiffness nor glass-transition temperature (Tg) lowering occurs upon CFRP nanomodification. Stable noncrosslinked nanofibers with up to 60% wt of NBR were produced via single-needle electrospinning, which were then morphologically, thermally, spectroscopically, and mechanically characterized. NBR and Nomex disposition in the nanofiber was investigated via selective removal of the sole rubber fraction, revealing the formation of particular self-assembled structures resembling quasi-core-shell nanofibers or fibril-like hierarchical structures, depending on the applied electrospinning conditions (1.10 and 0.20 mL/h, respectively). Mode I and Mode II loading tests show a significant improvement of the interlaminar fracture toughness of rubbery nanofiber-modified CFRPs, especially GI (up to +180%), while GII enhancement is less pronounced but still significant (+40% in the best case). The two nanofibrous morphologies (quasi-core-shell and fibril-like ones) improve the delamination resistance differently, also suggesting that the way the rubber is located in the nanofibers plays a role in the toughening action. The quasi-core-shell nanofiber morphology provides the best reinforcing action, besides the highest productivity. By contrast, pure Nomex nanofibers dramatically worsen the interlaminar fracture toughness (up to -70% in GI), acting as a release film. The achieved delamination resistance improvements, combined with the retention of both the original laminate stiffness and Tg, pave the way to the extensive and reliable application of NBR/Nomex rubbery nanofibrous mats in composite laminates.

Development and validation of a delirium risk assessment tool in older patients admitted to the Emergency Department Observation Unit

BACKGROUND

Delirium is frequent though undetected in older patients admitted to the Emergency Department (ED).

AIMS

To develop and validate a delirium risk assessment tool for older persons admitted to the ED Observation Unit (OU).

METHODS

We used data from two samples of 65 + year-old patients, one admitted to the ED of Brescia Hospital (n = 257) and one to the ED of Desio Hospital (n = 107), Italy. Data from Brescia were used as training sample, those collected in Desio as testing one. Delirium was assessed using the 4AT and patients' characteristic were retrieved from medical charts. Variables found to be associated with delirium in the training sample were tested for the creation of a delirium risk assessment tool. The resulting tool's performances were assessed in the testing subsample.

RESULTS

Of all possible scores tested, the combination with the highest discriminative ability in the training sample included: age ≥ 75 years, dementia diagnosis, chronic use of neuroleptics, and hearing impairment. The delirium score exhibited an AUC of 0.874 and 0.893 in the training and testing samples, respectively. For a 1-point increase in the score, the odds of delirium increased more than twice in both samples.

DISCUSSION

We propose a delirium risk assessing tool that includes variables that can be easily collected at ED admission and that can be calculated rapidly.

CONCLUSION

A risk assessment tool could help improving delirium detection in older persons referring to ED.

Rubbery-Modified CFRPs with Improved Mode I Fracture Toughness: Effect of Nanofibrous Mat Grammage and Positioning on Tanδ Behaviour

Carbon Fiber Reinforced Polymers (CFRPs) are widely used where high mechanical performance and lightweight are required. However, they suffer from delamination and low damping, severely affecting laminate reliability during the service life of components. CFRP laminates modified by rubbery nanofibers interleaving is a recently introduced way to increase material damping and to improve delamination resistance. In this work, nitrile butadiene rubber/poly(ε-caprolactone) (NBR/PCL) blend rubbery nanofibrous mats with 60 wt% NBR were produced in three different mat grammages (5, 10 and 20 g/m²) via single-needle electrospinning and integrated into epoxy CFRP laminates. The investigation demonstrated that both mat grammage and positioning affect CFRP tanδ behaviour, evaluated by dynamic mechanical analysis (DMA) tests, as well as the number of nano-modified interleaves. Double cantilever beam (DCB) tests were carried out to assess the mat grammage effect on the interlaminar fracture toughness. Results show an outstanding improvement of G_I,R for all the tested reinforced laminates regardless of the mat grammage (from +140% to +238%), while the effect on G_I,C is more dependent on it (up to +140%). The obtained results disclose the great capability of NBR/PCL rubbery nanofibrous mats at improving CFRP damping and interlaminar fracture toughness. Moreover, CFRP damping can be tailored by choosing the number and positioning of the nano-modified interleaves, besides choosing the mat grammage.

Why data on frailty and SARS-CoV-2 infection are basic to progress

Several studies showed that frailty was a predictor of in-hospital death in older adults with COVID-19. The mechanisms through which frailty increases the severity of COVID-19 are several, including immunosenescense and dysregulated inflammation. Whether individuals affected by frailty exhibit a higher susceptibility to SARS-CoV-2 infection remains an open question. Here we report the case series of 40 older persons that in February 2020, before the first case of COVID-19 was detected in Italy, went together on a winter holiday. Back home, 7 of them developed influenza-like symptoms and one was hospitalized due to COVID-19 pneumonia. Between May and July, the seniors were offered the possibility to be tested for SARS-CoV-2 antibody positivity. Twenty-seven of them accepted: 13 had a positive serological test whereas no active infection was found. Comparing the characteristics of those who tested positive and the others, we found that the former group was frailer, exhibiting higher Clinical Frailty Scale scores.

Tuning the Structure of Nylon 6,6 Electrospun Bundles to Mimic the Mechanical Performance of Tendon Fascicles

Tendon and ligament injuries are triggered by mechanical loading, but the specific mechanisms are not yet clearly identified. It is well established however, that the inflection and transition points in tendon stress-strain curves represent thresholds that may signal the onset of irreversible fibrillar sliding. This phenomenon often results in a progressive macroscopic failure of these tissues. With the aim to simulate and replace tendons, electrospinning has been demonstrated to be a suitable technology to produce nanofibers similar to the collagen fibrils in a mat form. These nanofibrous mats can be easily assembled in higher hierarchical levels to reproduce the whole tissue structure. Despite the fact that several groups have developed electrospun tendon-inspired structures, an investigation of the inflection and transition point mechanics is missing. Comparing their behavior with that of the natural counterpart is important to adequately replicate their behavior at physiological strain levels. To fill this gap, in this work fascicle-inspired electrospun nylon 6,6 bundles were produced with different collector peripheral speeds (i.e., 19.7 m s^–1; 13.7 m s^–1; 7.9 m s^–1), obtaining different patterns of nanofibers alignment. The scanning electron microcopy revealed a fibril-inspired structure of the nanofibers with an orientation at the higher speed similar to those in tendons and ligaments (T/L). A tensile mechanical characterization was carried out showing an elastic-brittle biomimetic behavior for the higher speed bundles with a progressively more ductile behavior at slower speeds. Moreover, for each sample category the transition and the inflection points were defined to study how these points can shift with the nanofiber arrangement and to compare their values with those of tendons. The results of this study will be of extreme interest for the material scientists working in the field, to model and improve the design of their electrospun structures and scaffolds and enable building a new generation of artificial tendons and ligaments.

Tissue Engineering for the Insertions of Tendons and Ligaments: An Overview of Electrospun Biomaterials and Structures

The musculoskeletal system is composed by hard and soft tissue. These tissues are characterized by a wide range of mechanical properties that cause a progressive transition from one to the other. These material gradients are mandatory to reduce stress concentrations at the junction site. Nature has answered to this topic developing optimized interfaces, which enable a physiological transmission of load in a wide area over the junction. The interfaces connecting tendons and ligaments to bones are called entheses, while the ones between tendons and muscles are named myotendinous junctions. Several injuries can affect muscles, bones, tendons, or ligaments, and they often occur at the junction sites. For this reason, the main aim of the innovative field of the interfacial tissue engineering is to produce scaffolds with biomaterial gradients and mechanical properties to guide the cell growth and differentiation. Among the several strategies explored to mimic these tissues, the electrospinning technique is one of the most promising, allowing to generate polymeric nanofibers similar to the musculoskeletal extracellular matrix. Thanks to its extreme versatility, electrospinning has allowed the production of sophisticated scaffolds suitable for the regeneration of both the entheses and the myotendinous junctions. The aim of this review is to analyze the most relevant studies that applied electrospinning to produce scaffolds for the regeneration of the enthesis and the myotendinous junction, giving a comprehensive overview on the progress made in the field, in particular focusing on the electrospinning strategies to produce these scaffolds and their mechanical, in vitro, and in vivo outcomes.

Towards Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene)-Based Soft Actuators: Films and Electrospun Aligned Nanofiber Mats

In the pursuit of designing a linear soft actuator with a high force-to-weight ratio and a stiffening behavior, this paper analyzes the electrostrictive effect of the poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) polymer in the form of film and aligned electrospun nanofiber mat. An experimental setup is realized to evaluate the electrostrictive effect of the specimens disjointly from the Maxwell stress. In particular, an uniaxial load test is designed to evaluate the specimens' forces produced by their axial contraction (i.e., the electrostrictive effect) when an external electric field is applied, while an uniaxial tensile load test is designed to show the specimens' stiffening properties. This electro-mechanical analysis demonstrates that both the film and the nanofiber mat are electrostrictive, and that the nanofiber mat exhibits a force-to-weight ratio ∼65% higher than the film and, therefore, a larger electrostrictive effect. Moreover, both the film and the nanofiber mat show a stiffening behavior, which is more evident for the nanofiber mat than the film and is proportional to the weight of the material. This study concludes that, thanks to its electro-mechanical properties, the poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene), especially in the form of aligned electrospun nanofiber mat, has high potential to be used as electro-active polymer for soft actuators in biomedical and biorobotics applications.

High-resolution X-ray tomographic workflow to investigate the stress distribution in vitreous enamel steels

Vitreous enamel steels (VES) are a class of metal-ceramic composite materials realised with a low carbon steel basement coated by an enamel layer. During the firing phase to adhere the enamel to the metal, several gas bubbles remain entrapped inside the enamel volume modifying its internal structure. In this work high-resolution X-ray computed tomography (micro-CT) was used to investigate these composite materials. The micro-CT reconstructions enabled a detailed investigation of VES minimising the metal artefacts. The tomograms were used to develop finite element models (FEM) of VES by means of a representative volume element (RVE) to evaluate the thermal residual stresses caused by the manufacturing process, as well as the effect of the 3D bubbles distribution on the internal stress patterns after the thermic gradient. The promising results from this study have the potential to inform further research on such composite materials by optimising manufacturing processes for targeted applications.

Biomimetic Hierarchically Arranged Nanofibrous Structures Resembling the Architecture and the Passive Mechanical Properties of Skeletal Muscles: A Step Forward Toward Artificial Muscle

Skeletal muscles are considered to date the best existing actuator in nature thanks to their hierarchical multiscale fibrous structure capable to enhance their strength and contractile performances. In recent years, driven by the growing of the soft robotics and tissue-engineering research field, many biomimetic soft actuators and scaffolds were designed by taking inspiration from the biological skeletal muscle. In this work we used the electrospinning technique to develop a hierarchically arranged nanofibrous structure resembling the morphology and passive biomechanical properties of skeletal muscles. To mimic the passive properties of muscle, a low-modulus polyurethane was used. Several electrospun structures (mats, bundles, and a muscle-like assembly) were produced with different internal 3D arrangements of the nanofibers. A thermal characterization through thermogravimetric and differential scanning calorimetry analysis investigated the physico-chemical properties of the material. The multiscale morphological similarities with the biological counterpart were verified by means of scanning electron microscopy investigation. The tensile tests on the different electrospun samples revealed that the muscle-like assembly presented slightly higher strength and stiffness compared to the skeletal muscle ones. Moreover, mathematical models of the mechanical behavior of the nanofibrous structures were successfully developed, allowing to better investigate the relationships between structure and mechanics of the samples. The promising results suggest the suitability of this hierarchical electrospun nanofibrous structure for applications in regenerative medicine and, if combined with active materials, in soft actuators for robotic.

Hierarchical electrospun tendon-ligament bioinspired scaffolds induce changes in fibroblasts morphology under static and dynamic conditions

The regeneration of injured tendons and ligaments is challenging because the scaffolds needs proper mechanical properties and a biomimetic morphology. In particular, the morphological arrangement of scaffolds is a key point to drive the cells growth to properly regenerate the collagen extracellular matrix. Electrospinning is a promising technique to produce hierarchically structured nanofibrous scaffolds able to guide cells in the regeneration of the injured tissue. Moreover, the dynamic stretching in bioreactors of electrospun scaffolds had demonstrated to speed up cell shape modifications in vitro. The aim of the present study was to combine different imaging techniques such as high-resolution X-ray tomography (XCT), scanning electron microscopy (SEM), fluorescence microscopy and histology to investigate if hierarchically structured poly (L-lactic acid) and collagen electrospun scaffolds can induce morphological modifications in human fibroblasts, while cultured in static and dynamic conditions. After 7 days of parallel cultures, the results assessed that fibroblasts had proliferated on the external nanofibrous sheath of the static scaffolds, elongating themselves circumferentially. The dynamic cultures revealed a preferential axial orientation of fibroblasts growth on the external sheath. The aligned nanofibre bundles inside the hierarchical scaffolds instead, allowed a physiological distribution of the fibroblasts along the nanofibre direction. Inside the dynamic scaffolds, cells appeared thinner compared with the static counterpart. This study had demonstrated that hierarchically structured electrospun scaffolds can induce different fibroblasts morphological modifications during static and dynamic conditions, modifying their shape in the direction of the applied loads. LAY DESCRIPTION: To enhance the regeneration of injured tendons and ligaments cells need to growth on dedicated structures (scaffolds) with mechanical properties and a fibrous morphology similar to the natural tissue. In particular, the morphological organisation of scaffolds is fundamental in leading cells to colonise them, regenerating the collagen extracellular matrix. Electrospinning is a promising technique to produce fibres with a similar to the human collagen fibres, suitable to design complex scaffolds able to guide cells in the reconstruction of the natural tissue. Moreover, it is well established that the cyclic stretching of these scaffolds inside dedicated systems called bioreactors, can speed up cells growth and their shape modification. The aim of the present study was to investigate how hierarchically structured electrospun scaffolds, made of resorbable material such as poly(L-lactic acid) and collagen, could induce morphological changes in human fibroblasts, while cultured during static and dynamic conditions. These scaffolds were composed by an external electrospun membrane that grouped inside it a ring-shaped bundle, made of axially aligned nanofibres, resembling the morphological arrangement of tendon and ligament tissue. After 7 days of parallel cultures, the scaffolds were investigated using the following imaging techniques: (i) high-resolution X-ray tomography (XCT); (ii) scanning electron microscopy (SEM); (iii) fluorescence microscopy and (iv) histology. The results showed that fibroblasts were able to grow on the external nanofibrous sheath of the static scaffolds, by elongating themselves along their circumference. The dynamic cultures revealed instead a preferential axial orientation of fibroblasts grown on the external sheath. The aligned nanofibre bundles inside the hierarchical scaffolds allowed an axial distribution of the fibroblasts along the nanofibres direction. This study has demonstrated that the electrospun hierarchically structured scaffolds investigated can modify the fibroblasts morphology both in static and dynamic conditions, in relation with the direction of the applied loads.

Morphologically bioinspired hierarchical nylon 6,6 electrospun assembly recreating the structure and performance of tendons and ligaments

Reconstructions of ruptured tendons and ligaments currently have dissatisfactory failure rate. Failures are mainly due to the mechanical mismatch of commercial implants with respect to the host tissue. In fact, it is crucial to replicate the morphology (hierarchical in nature) and mechanical response (highly-nonlinear) of natural tendons and ligaments. The aim of this study was to develop morphologically bioinspired hierarchical Nylon 6,6 electrospun assemblies recreating the structure and performance of tendons and ligaments. First, we built different electrospun bundles to find the optimal orientation of the nanofibers. A 2nd-level hierarchical assembly was fabricated with a dedicated process that allowed tightly joining the bundles one next to the other with an electrospun sheath, so as to improve the mechanical performance. Finally, a further hierarchical 3rd-level assembly was constructed by grouping several 2nd-level assemblies. The morphology of the different structures was assessed with scanning electron microscopy and high-resolution X-ray tomography, which allowed measuring the directionality of the nanofibers in the bundles and in the sheaths. The mechanical properties of the single bundles and of the 2nd-level assemblies were measured with tensile tests. The single bundles and the hierarchical assemblies showed morphology and directionality of the nanofibers similar to the tendons and ligaments. The strength and stiffness were comparable to that of tendons and ligaments. In conclusion, this work showed an innovative electrospinning production process to build nanofibrous Nylon 6,6 hierarchical assemblies which are suitable as future implantable devices and able to mimic the multiscale morphology and the biomechanical properties of tendons and ligaments.

Tendon Fascicle-Inspired Nanofibrous Scaffold of Polylactic acid/Collagen with Enhanced 3D-Structure and Biomechanical Properties

Surgical treatment of tendon lesions still yields unsatisfactory clinical outcomes. The use of bioresorbable scaffolds represents a way forward to improve tissue repair. Scaffolds for tendon reconstruction should have a structure mimicking that of the natural tendon, while providing adequate mechanical strength and stiffness. In this paper, electrospun nanofibers of two crosslinked PLLA/Collagen blends (PLLA/Coll-75/25, PLLA/Coll-50/50) were developed and then wrapped in bundles, where the nanofibers are predominantly aligned along the bundles. Bundle morphology was assessed via SEM and high-resolution x-ray computed tomography (XCT). The 0.4-micron resolution in XCT demonstrated a biomimetic morphology of the bundles for all compositions, with a predominant nanofiber alignment and some scatter (50-60% were within 12° from the axis of the bundle), similar to the tendon microstructure. Human fibroblasts seeded on the bundles had increased metabolic activity from day 7 to day 21 of culture. The stiffness, strength and toughness of the bundles are comparable to tendon fascicles, both in the as-spun condition and after crosslinking, with moderate loss of mechanical properties after ageing in PBS (7 and 14 days). PLLA/Coll-75/25 has more desirable mechanical properties such as stiffness and ductility, compared to the PLLA/Coll-50/50. This study confirms the potential to bioengineer tendon fascicles with enhanced 3D structure and biomechanical properties.

Nanovascularization of polymer matrix: generation of nanochannels and nanotubes by sacrificial electrospun fibers

Several methods for creating vascular structures, made of either discrete or interconnected channels have been developed. The currently employed methods enable the formation of channels with diameters in the millimetric and micrometric scale. However, the formation of an interconnected three-dimensional (3D) vasculature by using a rapid and scalable process is a challenge and largely limits the fields of applicability of these innovative materials. Here, we propose the use of electrospun nonwoven mats as sacrificial fibers to easily generate 3D macroscale vascularized composites containing interconnected networks with channels and tubes having submicrometric and nanometric diameters. The novel approach has the potentialities to give rise to a novel generation of composites potentially displaying new and enhanced functionalities thanks to the nanoscale features of the cavities.

Prometheus System: A Technological Support in Liver Failure

The Prometheus system is a plasma filtration treatment coupling adsorption and hemodialysis (FPSA) aimed to blood purification in liver failure. After separation through an albumin-permeable membrane, plasma enters a secondary circuit where protein-bound toxic substances are removed by two adsorbers; p01, a neutral resin, and p02, an anion exchanger. Plasma is then returned to the venous line, where a high-flux hemodialyzer removes water-soluble substances. We used the Prometheus system in 12 patients with acute or acute-on-chronic liver insufficiency: eight cirrhosis, one posttransplant dysfunction, and three secondary liver insult (two cardiogenic shock and one rhabdomyolysis). All patients were severely hyperbilirubinemic, hypercholemic, and hyperammonemic. Twenty-eight sessions each lasting 340 +/- 40 minutes were performed (2.5/patient). The mean total bilirubin decreased from 33.6 +/- 20 to 22.2 +/- 13.6 mg/dL (P < .001); the reduction ratios for cholic acid and ammonia were 48.6% and 51.6%, respectively. The pre- to postsession urea reduction was 57.6% +/- 9.5% and creatinine 42.7% +/- 10%. A significant reduction was observed in the circulating levels of soluble interleukin (IL) 2 receptor (pre: 2687.2 +/- 1434.7; post: 1977.1 +/- 602 Ul/ml; P < .001) and in IL 6 (pre: 56.1 +/- 11.1; post: 35.9 +/- 10.3 pg/mL, P = .05). During treatments the hemodynamics were stable. Two patients received liver transplantations. The secondary liver insult was completely overcome in all three patients. The overall survival at 30 days was 41.6% (5/12 patients). Prometheus, based on FPSA, produced high clearance for protein-bound and water soluble markers, which resulted in high treatment efficacy.

Renovascular disease in diabetes mellitus: treatment by percutaneous transluminal renal angioplasty

BACKGROUND

Diabetes mellitus is an important cause of end-stage renal failure (ESRF). Although classic diabetic nephropathy accounts for the majority of patients reaching ESRF, renovascular disease, which is frequent in such patients, plays an increasingly important role. Percutaneous transluminal renal angioplasty (PTRA) has been proven to be an efficacious measure for renal revascularization.

METHODS

Ninety-nine patients with diabetes mellitus and renal artery stenosis, corresponding to 16.6% of the entire population of diabetic patients, were treated by PTRA or with the Palmaz-Schatz stent in our clinic. Technical success was achieved by PTRA in 92/99 patients, in 10 patients a Palmaz-Schatz stent was implanted.

RESULTS

Hypertension was cured in eight and improved in 44 patients. In 47 patients, there was no impact on blood pressure. An improvement in renal function was evident 1 month after PTRA in 8/27 patients. A further improvement occurred in another four patients after 6 months. The re-stenosis rate was 22% after 5 years. Serious complications occurred in seven patients (one patient required surgery and two patients had regular dialysis treatment).

CONCLUSIONS

Renovascular disease is an important cause of ESRF in diabetic patients. PTRA is a valid tool to revascularize renal artery stenosis and improve blood pressure control and renal function both in diabetic and non-diabetic patients.

Lupus membranous nephropathy: long-term outcome

The follow-up of 42 patients affected by lupus membranous nephropathy (LMN) is reported and compared with that of 43 patients affected by diffuse proliferative lupus glomerulonephritis (DPGN), who were the object of a previous study. According to the WHO classification, the patients were subdivided into two groups: pure LMN (Va + Vb class) and LMN with superimposed proliferative lesions (Vc + Vd class). Antiphospholipid antibodies (APA) and lupus anticoagulant were tested in 23 subjects. All the patients were treated with corticosteroids, which were associated to cytotoxic drugs in 28 cases. Although a higher number of complete remissions was obtained in patients with pure LMN, the difference between the 2 groups was not significant (7/26 vs 1/16). At 10 years kidney survival was 93% in all LMN patients with no significant differences between the 2 groups. This 10-year kidney survival rate is very similar to that previously observed by us for DPGN (91%). The WHO histological classification and the chronicity index did not identify the patients who reach end-stage renal failure. Eight patients suffered from thrombotic manifestations which were the cause of death in two cases. Fourteen of the 20 patients studied presented echocardiographic abnormalities. A statistically significant association was found between the occurrence of cardiovascular complications and APA levels. The effectiveness of treatment in LMN remains controversial. We suggest, however, that adequate therapy may significantly improve the prognosis of lupus nephritis thus reducing the differences in the outcome of SLE patients having different histological WHO classes. Cardiovascular illness represents a frequent and severe late complication.

Lymphocyte release of soluble IL-2 receptors in patients with minimal change nephropathy

Minimal change nephrotic syndrome has been reported to be a lymphocyte-mediated disorder. It has been suggested that the secretion of lymphokine(s) is involved in the pathogenesis of MCN and in determining proteinuria. The presence of a soluble form of IL-2 receptor (sIL-2R) has been previously described in the sera of patients with some autoimmune disorders. In this work, we report the detection of high sIL-2R levels, both in the plasma (mean value 844 +/- 436 U/ml versus normal value 276 +/- 86 U/ml) and urine of patients with MCN during the nephrotic phase alone. Instead, when the patients achieve stable remission, sIL-2R levels decrease to within normal values (mean value 332 +/- 272 U/ml). Furthermore, during the nephrotic syndrome we observed a significant inverse relationship between sIL-2R plasma levels and the mitogenic response to PHA (p less than 0.005). Since sIL-2R exerts a down-modulation on T-proliferative expansion, sIL-2R might represent one of the inhibitory serum factors extensively reported in the serum of patients with MCN-induced nephrotic syndrome.

Long-term survival patients with acute and severe renal failure due to multiple myeloma

We selected 37 cases, followed-up for more than 36 months or until death, from a series of 45 patients affected by acute renal failure due to multiple myeloma in order to identify the parameters that could allow the outcome to be predicted. The patients were allocated to group 1, consisting of 27 patients who died within one year and to group 2, consisting of 10 patients who survived for more than 36 months. Renal failure was severe enough to require dialysis in 28 patients, 16 of whom were oliguric. Renal biopsy was performed in 23 cases, whereas light chain isoelectric point and serum beta 2-microglobulin levels were evaluated in each patient. All the patients underwent chemotherapy, which was associated with plasma exchange in 16 patients. Statistical analysis of the potential prognostic factors in the 2 groups showed that the incidence of hypercalcemia, infection, irreversible renal failure and severe tubulo-interstitial damage was significantly higher in group 1. Sex, tumor load, severity of renal failure and light chain isoelectric point had no prognostic significance. Finally, the number of patients treated by plasma exchange was significantly higher in group 2. Our results underline the prognostic role of both hypercalcemia and infection and justify aggressive treatment consisting of chemotherapy, plasma exchange and dialysis, even in cases of severe renal failure and high tumor load.

Acute bilateral renal vein thrombosis superimposed on calcified thrombus of the inferior vena cava in a patient with membranous lupus nephritis

We report a case of membranous lupus nephritis with a previous history of long-standing nephrotic syndrome which developed an acute renal failure due to bilateral renal-vein thrombosis superimposed on a calcified thrombus of the inferior vena cava eight years after the diagnosis. The occurrence of acute renal-vein thrombosis is a possible but rarely described complication of systemic lupus erythematosus. The presence of a calcified thrombus of the inferior vena cava has been described in only one adult patient until now. An aggressive thrombolytic therapy with urokinase permitted the fresh thrombus to be dissolved with a marked improvement in renal function.

Renal functional reserve in patients with a reduced number of functioning glomeruli

Renal functional reserve (RFR) has been reported to be either reduced or absent in patients with renal insufficiency. Our study consisted in measuring RFR by acute protein load (PL) in 3 groups of patients: the first one was composed of 20 patients (pts) with biopsy-proven glomerular disease (GN) and a varying percentage of sclerotic glomeruli (15-70%); the second one consisted of 10 patients with acquired single kidney (SK) and the third group contained 5 patients with surgical ablation of more than 50% renal tissue (LRRM). Twenty-four healthy volunteers were studied as control subjects. The GFR percentage increase (delta GFR%) after PL in CS did not differ from that of the three groups of patients, despite a significant difference in resting GFR (CS = 113 +/- 11 ml/min/1.73 m2: GN 72 +/- 28 ml/min/1.7, p less than 0.01 vs CS; SK 81 +/- 20 ml/min/1.73 m2, p less than 0.01 vs CS; LRRM 45 +/- 10 ml/min/1.7, p less than 0.01 vs CS; Moreover, an inverse correlation was not found either between GFR and the percentage of sclerotic glomeruli in GN (r = 0.01, p = NS) or between GFR and the extent of excised renal tissue in the other two groups (r = 0.38, p = NS). In conclusion, our data do not confirm that RFR is necessarily reduced or absent in patients with a reduced number of functioning glomeruli, nor do they uphold the hypothesis of constant hyperfiltration in the remaining glomeruli.

[Study of 357 cases of phlebitis of the lower extremities in 2 inter-regional samplings. II. Clinical and diagnostic data and therapeutic conclusions]

In Piedmont, the incidence of superficial and deep forms is the same percentage-wise. In the Trento area, however, deep forms are more common, though no significant differences can be discerned with respect to the side affected, the site (other than that related to the type of phlebitis), or the symptoms. At least one complication was noted in 241-261 and 27-96 cases in Piedmont and Trento respectively. The treatment initially employed proved inadequate. The risks involved are known solely with respect to patients with complications. The resort to surgical management was much more frequent in the Trento region. An attempt is made to evaluate the risk factors associated with thrombophlebitis of the lower limbs, and the measure of agreement between the aetiopathogenetic, clinical and therapeutic data obtained for the two regions.

[Study of 357 cases of phlebitis of the lower extremities in 2 inter-regional samplings. I. Methods, epidemiological data and analysis of etiopathogenetic elements]

Using a specially designed record card, 357 cases of superficial and deep thrombophlebitis and phlebothrombosis of the lower extremities have been investigated. Of these 261 were observed in Piedmont and 96 in the Trentino region. A comparative study of aetiopathogenetic data in the two regions was made possible by means of punched cards and subsequent computer processing. The study was completed by statistical analysis. Apart from the region of birth and residence, sex (prevalently female) and age which in both samples mainly affects subjects aged between 30 and 45, the type of working activity was considered in relation to sex and age, frequency of absenteeism (higher in Piedmont), family history of venous disease, incidence of orthostatism, the use of contraceptive pills, the period in which the first clinical signs occurred with considerable diversity between the two regions, traumas (more frequent in Piedmont) and the incidence of the different causes which was vastly different in the two samples, were assessed. On the basis of the comparative data obtained, an interpretation of the real significance of the results is attempted, reference also being made to the type of population under examination, the Piedmontese being considered of mixed strain and the Trentino pure.