Optimization of Electrospun Bilayer Vascular Grafts through Assessment of the Mechanical Properties of Monolayers.

Small-diameter vascular grafts must be obtained with the most appropriate materials and design selection to harmoniously display a variety of features, including adequate tensile strength, compliance, burst strength, biocompatibility, and biodegradability against challenging physiological and hemodynamic conditions. In this study, monolayer vascular grafts with randomly distributed or radially oriented fibers are produced using neat, blended, and copolymer forms of polycaprolactone (PCL) and poly(lactic acid) (PLA) via the electrospinning technique. The blending ratio is varied by increasing 10 in the range of 50-100%. Bilayer graft designs are realized by determining the layers with a random fiber distribution for the inner layer and radial fiber orientation for the outer layer. SEM analysis, wall thickness and fiber diameter measurements, tensile strength, elongation, burst strength, and compliance tests are done for both mono- and bilayer scaffolds. The findings revealed that the scaffolds made of neat PCL show more flexibility than the neat PLA samples, which possess higher tensile strength values than neat PCL scaffolds. Also, in blended samples, the tensile strength values do not show a significant improvement, whereas the elongation values are enhanced in tubular samples, depending on the blending ratio. Also, neat poly(l-lactide-co-caprolactone) (PLCL) samples have both higher elongation and strength values than neat and blended scaffolds, with some exceptions. The blended specimens comprising a combination of PCL and PLA, with blending ratios of 80/20 and 70/30, exhibited the most elevated burst pressures. Conversely, the PLCL scaffolds demonstrated superior compliance levels. These findings suggest that the blending approach and fiber orientation offer enhanced burst strength, while copolymer utilization in PLCL scaffolds without fiber alignment enhances their compliance properties. Thus, it is evident that using a copolymer instead of blending PCL and PLA and combining the PLCL layer with PCL and PLA monolayers in bilayer vascular graft design is promising in terms of mechanical and biological properties.

Investigation of biodegradability and cellular activity of PCL/PLA and PCL/PLLA electrospun webs for tissue engineering applications.

Biodegradability and cellular activity are key performance indicators that should be prioritized for tissue engineering applications. Biopolymer selection, determination of necessary structural properties, and their synergistic interactions play an active role in obtaining the expected biodegradability and biological activity from scaffolds. In this study, it is aimed to produce electrospun webs with improved biocompatibility by blending polycaprolactone (PCL) with polylactic acid (PLA) and poly-l-lactide (PLLA), and examine the effect of biopolymer selection and blend ratio on the biodegradability and cellular activity of surfaces. In this context, fibrous webs are produced from PCL/PLA and PCL/PLLA blends with a weight ratio of 80/20 and 50/50 and pure polymers of PCL, PLA, and PLLA by electrospinning method and subjected to morphological and biological analyses. The biodegradation tests are carried out hydrolytically while the cell viability and cell proliferation analyses are performed with adult human primary dermal fibroblasts and human umbilical endothelial cells (HUVECs). The results show that the fiber diameters of the fabricated webs ranged from 0.747 to 1.685 µm. At the end of the 5th month, it is observed that the biodegradation rates of the webs blended 50% with PLA and PLLA, in comparison to PCL ones, increase from 3.7% to 13.33% and 7.69%, respectively. On the other hand, cell culture results highlight that the addition of 20% PLA and PLLA improves the cellular activity of both cell types, but increased PLA or PLLA ratio in PCL webs has a negative effect as it makes the structure stiff and brittle.

An Investigation of the Constructional Design Components Affecting the Mechanical Response and Cellular Activity of Electrospun Vascular Grafts.

Cardiovascular disease is anticipated to remain the leading cause of death globally. Due to the current problems connected with using autologous arteries for bypass surgery, researchers are developing tissue-engineered vascular grafts (TEVGs). The major goal of vascular tissue engineering is to construct prostheses that closely resemble native blood vessels in terms of morphological, mechanical, and biological features so that these scaffolds can satisfy the functional requirements of the native tissue. In this setting, morphology and cellular investigation are usually prioritized, while mechanical qualities are generally addressed superficially. However, producing grafts with good mechanical properties similar to native vessels is crucial for enhancing the clinical performance of vascular grafts, exposing physiological forces, and preventing graft failure caused by intimal hyperplasia, thrombosis, aneurysm, blood leakage, and occlusion. The scaffold's design and composition play a significant role in determining its mechanical characteristics, including suturability, compliance, tensile strength, burst pressure, and blood permeability. Electrospun prostheses offer various models that can be customized to resemble the extracellular matrix. This review aims to provide a comprehensive and comparative review of recent studies on the mechanical properties of fibrous vascular grafts, emphasizing the influence of structural parameters on mechanical behavior. Additionally, this review provides an overview of permeability and cell growth in electrospun membranes for vascular grafts. This work intends to shed light on the design parameters required to maintain the mechanical stability of vascular grafts placed in the body to produce a temporary backbone and to be biodegraded when necessary, allowing an autologous vessel to take its place.

Development of biodegradable webs of PLA/PCL blends prepared via electrospinning: Morphological, chemical, and thermal characterization.

Biodegradable polymers have a mean role to mimic native tissues and allow cells to penetrate, grow, and proliferate with their advanced features in tissue engineering applications. The physiological, chemical, mechanical, and biological qualities of the surfaces, which are presented from biodegradable polymers, affect the final properties of the scaffolds. In this study, it is aimed to produce fibrous webs by electrospinning method for tissue engineering applications using two different biopolymers, polylactic acid (PLA) and polycaprolactone (PCL). These polymers are used either alone or in a blended form (PLA/PCL, 1/1 wt.). Within the scope of the study, polymer concentrations (6, 8 and 10%) and solvent types (used for chloroform/ethanol/acetic acid mixture, PCL and PLA/PCL mixtures, and chloroform/acetone, PLA) vary as solution parameters. Fibrous webs are investigated in terms of morphological, chemical, and thermal characteristics. Results show continuous fibers are examined for 8 or 10% polymer concentrations with an average fiber diameter of 1.3-2.7 µm and pore area of 4-9 µm2 . No fiber formation is observed in sample groups with a polymer concentration of 6% and beaded structures are formed. Water contact angle analysis proves the hydrophobic properties of PLA and PCL, whereas Fourier-transform infrared results show there is no solution residue on the surfaces, so there is no toxic effect. Also, in differential scanning calorimetry analysis, the characteristic crystallization peaks of the polymers are recognized, and when the polymers are in a blend, it beholds that they have effects on each other's crystallization.

How can periorbital oedema and ecchymose be reduced in rhinoplasty?

Oedema and ecchymose are frequent morbidities of septorhinoplasty, a facial surgical procedure for reforming the shape and functions of the nose. Periorbital oedema (PO) and periorbital ecchymose (PE) are normal occurrences, but are undesirable for patients undergoing the procedure for aesthetic purposes. The present study examined 65 patients who underwent open technique septorhinoplasty for aesthetic and functional complaints. Patients were divided into two groups: Group 1 patients underwent lateral osteotomy following tip plasty, at the end of the surgical operation; Group 2 patients underwent lateral osteotomy before tip plasty, at the beginning of the surgical operation. Patients were followed on the postoperative first, third and seventh days. PO and PE values of patients were scored from 0 to 4. The plastering time (Pt) was significantly shorter for Group I than Group II (p < 0.05). The total surgical time (T) showed no significant difference (p > 0.05). The PO value at the first, third and seventh days was significantly smaller for Group I than Group II (p < 0.05). The PE value at the first, third and seventh days was also significantly smaller for Group I than Group II (p < 0.05). The obtained data indicate that performing a lateral osteotomy in the final stages of surgery, and subsequently applying a nasal plaster and splint as rapidly as possible, decreases PO and PE in the postoperative period.

Histopathologic changes in the middle ear mucosa after exposure to pepsin and unconjugated bile acid.

OBJECTIVE: An increasing number of studies indicate that pepsin and bile acid cause damage to the ear, nose, and throat structures as a result of extraesophageal reflux. The aim of this study was to evaluate and compare the damaging effect of bile acids and pepsin on the middle ear mucosa. MATERIAL AND METHODS: Twenty-nine healthy rats were included in this study. The animals were divided into 5 groups. A single daily dose of 40 µmol/L chenodeoxycholic acid, 40 µg/mL pepsin, and saline were injected separately into the right middle ear of the rats. On day 30, all rats were decapitated, and formalin-fixed, paraffin-embedded samples of the middle ear both from the control and experimental rats were prepared. A semiquantitative analysis was performed. RESULTS: Inflammatory response was seen in all middle ear mucosa of rats except control group 1. The degree of inflammatory response was higher in the bile acid group when compared with the other groups. Epithelial metaplastic changes with varying number of goblet cells were observed in both the bile acid- and pepsin-injected groups. These metaplastic changes were also higher in the bile acid-induced group than in the pepsin-injected group. CONCLUSIONS: This is the first study on the middle ear mucosal damage of both pepsin and bile acid. Our results demonstrate that bile acids were associated with more extensive mucosal injury at pH 7 in comparison to pepsin in a rat animal model. Inflammatory response and metaplastic changes may play an important role in the etiology of middle ear pathologies.

Effect of thermal welding tonsillectomy on emergence agitation.

: This study sought to examine the effect of thermal welding tonsillectomy that reduces pain and length of anesthesia on emergence agitation. A total of 60 patients (age range, 3­6 years) with chronic recurrent tonsillitis with an indication for tonsillectomy were included. Patients were randomly assigned to 2 groups. The control group (the CD group) was composed of patients undergoing cold dissection (CD) tonsillectomy. The study group (TW group) included patients undergoing thermal welding (TW) tonsillectomy. All patients were given sevoflurane as an anesthetic agent. For all patients, anesthesia time, operation time, extubation time, Pediatric Anesthesia Emergence Delirium scale, pain scale, nausea/vomiting score, and delivery time were recorded. The duration of anesthesia, operation, and delivery was significantly lower in the TW group as compared with the CD group (P = 0.000 < 0001). The pain and agitation scores were significantly lower in the TW group as compared with the CD group (P = 0.000 < 0001). We assume that, besides reducing pain and allowing surgery without bleeding, the TW tonsillectomy method diminishes emergence agitation induced by anesthetic agents, such as sevoflurane.

The effect of the duration of merocel in a glove finger on postoperative morbidity.

We examined the effects of the duration of keeping a Merocel nasal packing in the nose and the application technique (packing applied either directly or inside a glove finger) on postoperative morbidity and complications. The study included 129 patients (67 males and 62 females; age range 18 to 56 years) undergoing nasal septoplasty without turbinate intervention. The patients were randomly assigned into 4 groups. In group 1 and group 2, Merocel was directly applied in the nasal cavity for 24 hours and 48 hours, respectively; in group 3 and group 4, Merocel was kept in the nasal cavity in a powder-free glove finger for 24 hours and for 48 hours, respectively. Pain and discomfort scores were evaluated by a visual analog scale. The time taken between removal of the tampon and when the patients began to breathe comfortably was called the nasal obstruction time. The differences in mean discomfort score between the groups were not statistically significant (P > 0.05), while the mean pain scores were statistically higher in groups 1 and 2 than in groups 3 and 4 (P < 0.05). The nasal obstruction time was statistically shorter in groups 2 and 4 than in groups 1 and 3 (P < 0.05). Therefore, keeping Merocel inside a glove finger in place for 48 hours notably reduces the pain occurring during the removal of the nasal tampon. It also reduces nasal obstruction time and prevents synechia, leakage, bleeding, and septal hematoma, without compromising patient comfort.