Instytut Podstawowych Problemów Techniki

Streszczenie:

The purpose of this study was to compare: a new five-layered poly (L–lactide–co–caprolactone) (PLC) membrane and small intestinal submucosa (SIS) as a control in rat urinary bladder wall regeneration. The five-layered poly (L–lactide–co–caprolactone) membrane was prepared by an electrospinning process. Adipose tissue was harvested from five 8-week old male Wistar rats. Adipose derived stem cells (ADSCs) were seeded in a density of 3×106 cells/cm2 onto PLC membrane and SIS scaffolds, and cultured for 5-7 days in the stem cell culture medium. Twenty male Wistar rats were randomly divided into five equal groups. Augmentation cystoplasty was performed in a previously created dome defect. Groups: (I) PLC+ 3×106ADSCs; (II) SIS+ 3×106ADSCs; (III) PLC; (IV) SIS; (V) control. Cystography was performed after three months. The reconstructed urinary bladders were evaluated in H&E and Masson's trichrome staining. Regeneration of all components of the normal urinary bladder wall was observed in bladders augmented with cell-seeded SIS matrices. The urinary bladders augmented with SIS matrices without cells showed fibrosis and graft contraction. Bladder augmentation with the PLC membrane led to numerous undesirable events including: bladder wall perforation, fistula or diverticula formation, and incorporation of the reconstructed wall into the bladder lumen. The new five-layered poly (L–lactide–co–caprolactone) membrane possesses poorer potential for regenerating the urinary bladder wall compared with SIS scaffold.

Słowa kluczowe:

urinary bladder regeneration, electrospinning

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Streszczenie:

Excessive cicatrisation or epidural fibrosis in the operative field is an inappropriate event occasionally occurring after neurosurgical procedures (i.e., spine procedures and craniotomies). This excessive process may disturb the postopera­tive course and render reoperations more difficult and risky. The literature describes this phenomenon as accompanying up to 20% of neurosurgical procedures. The scar tissue that forms postoperatively adheres to the dura mater, penetrates into the spinal canal and can cause narrowing symptoms, neurological deficits and pain. The incidence and spread of this excessive scar or epidural fibrosis can be prevented through the modification of the surgical technique by incorporating endoscopic or microscopic access to minimize the operative field and the use of isolating substances (autogenous or heterogeneous) administered intraoperatively.

The aim of this experimental study was to morphologically assess the cicatrisation process, adhesion and to prevent excessive scar formation with the local use of membranes manufactured by an electrospinning process (nanotechnology). We also investigated whether the biodegradable nanofibrous net triggers or modifies the immunological response or the local inflammatory process.

Micro-nanofibrous membranes were produced by the electrospinning process. A biodegradable, medically certified copolymer poly(L-lactide-co-caprolactone) (PLCL) was used as the electrospun material.

An experimental rat model was used in this study. Experimental and control groups were formed with specified follow-up times of 4, 14 and 30 days. During the operation, a two-level laminectomy in the thoracic segment was performed. The operative field was divided into two regions. Isolating material was used on the dura mater and surface of the spinal cord in the area where the laminectomy was performed. The material was analysed with the use of light and electron microscopy.

Local cicatrisation can be modified using nanomaterials. Scar formation and epidural fibrosis can be limited and modi­fied locally. No local inflammation process was observed.

Initial observations indicate the potential for the effective use of materials obtained in the electrospinning process to prevent cicatrisation.

Słowa kluczowe:

neurosurgery, cicatrisation, epidural fibrosis, copolymer, poly(L-lactide-co-caprolactone), nanofibrous net, rat model

Afiliacje autorów:

Streszczenie:

The corrosion and erosion processes are detrimental to the lifetime and maintenance costs of steel combustion boilers in the energy sector. One of the remedies for this problem can be novel NiCr based coatings applied on structural elements, which are exposed to aggressive agents. NiCr alloys are known for their resistance to chemical and physical degradation in high temperature. Introducing a small admixture of rhenium and alumina ceramic to NiCr results in further increase of mechanical and wear properties of the coating. Three different deposition techniques were employed (HVOF, laser cladding and plasma spraying) to manufacture the coatings. The primary target of this research was to identify by experiments and numerical simulations the most promising deposition technique for the industrial application of the investigated coatings. Thermal residual stress measurements by XRD have shown that the lowest stresses occurred in the HVOF-deposited coating. The micro-CT based numerical simulations have confirmed this finding. The highest hardness was also manifested by the coating deposited by HVOF. The admixture of 10% vol. of Al2O3has improved the coating wear resistance. Remelting of powders during the laser cladding and low wettability of alumina were the main reasons of the unwished migration of ceramic particles towards the coating surface. A non-standard adhesion test was used to examine the coatings integrity and adhesion to the substrate. The obtained results point to the HVOF technique as the most promising of the three techniques considered. Moreover, HVOF can be easily implemented for complex shapes of the components.

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