Results of long-term permeability of small-diameter vascular prostheses modified by pro-angiogenic factors and athrombogenic drug coating (model of large laboratory animals)

Background. Preclinical tests of biodegradable small diameter vascular prostheses on a sheep model have been carried out.Aim. To assess the results of long-term patency and remodeling of biodegradable vascular prostheses based on polyhydroxybutyrate / valerate and polycaprolactone with an atrombogenic drug coating in a large laboratory animal model.Methods. We researched vascular prostheses made of polyhydroxybutyrate / valerate and polycaprolactone (PHBV/PCL) 4 mm in diameter with layer-by-layer vascular endothelial growth factor incorporated into the polymer framework, the main fibroblast growth factor, chemoattractant molecule containing SDF-1a (GFmix) surface, and additional modifying drug surface heparin and iloprost (PHBV/PCL/ GFmix/Heparin/Iloprost). Animals with implanted synthetic Gore-Tex vascular grafts with a diameter of 4 mm were included into a comparison group.Results. After one day of implantation it was revealed that the patency of biodegradable PHBV/PCL/GFmix/Heparin/Iloprost prostheses was 62.5%, while synthetic Gore-Tex prostheses were thrombosed in 100% of cases. At the same time, after 18 months of implantation, the patency of biodegradable vascular PHBV/PCL/ GFmix/Heparin/Iloprost prostheses decreased to 50%. Passable drug-eluting polymer grafts were completely resorbed after 18 months of implantation, and aneurysmically expanded newly formed vascular tissue was formed in their place.Conclusion. Vascular prostheses made of polyhydroxybutyrate/valerate and polycaprolactone showed better long-term patency results than synthetic prostheses used in the clinical practice. However, the strengthening of the external framework of the prostheses is required in order to prevent the formation of aneurysms.

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A Technology for Anti-Thrombogenic Drug Coating of Small-Diameter Biodegradable Vascular Prostheses

Sovremennye tehnologii v medicine ◽

10.17691/stm2020.12.6.01 ◽

2020 ◽

Vol 12 (6) ◽

pp. 6

Author(s):

L.V. Antonova ◽

E.O. Krivkina ◽

M.A. Rezvova ◽

V.V. Sevostyanova ◽

V.O. Tkachenko ◽

...

Keyword(s):

Small Diameter ◽

Vascular Prostheses ◽

Drug Coating

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Long-term and constant release of vasopressin from Accurel tubing: implantation in the Brattleboro rat

Journal of Endocrinology ◽

10.1677/joe.0.0980147 ◽

1983 ◽

Vol 98 (1) ◽

pp. 147-NP ◽

Cited By ~ 21

Author(s):

G. J. Boer ◽

J. Kruisbrink ◽

H. van Pelt-Heerschap

Keyword(s):

Small Diameter ◽

Laboratory Animals ◽

Subcutaneous Implantation ◽

Brattleboro Rat ◽

Urine Production

A long-lasting and constant release of vasopressin in serum solution (in vitro) for periods up to 50 days can be obtained by the use of small-diameter microporous Accurel polypropylene tubing, filled with vasopressin and covered with collodion. The potency of the preparation is shown in vivo after subcutaneous implantation in the adult vasopressin-deficient Brattleboro rat, for which normal levels of urine production and osmolality were achieved at least for 1 month. The possible use of this method for other peptides and its application in small or immature laboratory animals and in fetuses is emphasized.

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A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209409 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 951-958

Author(s):

Tianhao Liu ◽

Yu Jin ◽

Cuixiang Pei ◽

Jie Han ◽

Zhenmao Chen

Keyword(s):

Power Plants ◽

Signal To Noise Ratio ◽

Small Diameter ◽

Performance Testing ◽

Guided Wave ◽

High Signal ◽

Receiver Coil ◽

Signal To Noise ◽

Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

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Anesthesia for rabbits submitted to experimental surgeries: Report of a series of eight anesthesias

Panorama brasileiro de tungstênio (w) entre os anos de 2008 e 2014 ◽

10.32749/nucleodoconhecimento.com.br/health/anesthesia-for-rabbits ◽

2020 ◽

pp. 151-158

Author(s):

Rafael Antonio Caldart Bedin ◽

Maisa Schultz ◽

Antonio Bedin

Keyword(s):

Muscle Relaxation ◽

Anesthetic Management ◽

Laboratory Animals ◽

Average Weight ◽

Anesthetic Induction ◽

Anesthetic Agents ◽

Reasonable Degree ◽

Bioethical Debate ◽

Precordial Stethoscope

Anesthesia for laboratory animals is a matter of biomedical concern and one of the most present dilemmas in the current bioethical debate. The use of anesthetic agents in experimental surgery aims at analgesia and restraining the animal, in order to achieve a reasonable degree of muscle relaxation and to produce sufficient analgesia. This practice requires the use of protocols for the administration of safe and efficient doses. Eight New Zealand rabbits were submitted to laparotomies demonstrating the surgical technique discipline of the local medical course. For pre-anesthetic medication, acepromazine 1 mg.kg-1 associated with ketamine 15 mg.kg-1 was used subcutaneously. Anesthesia was maintained with isoflurane and oxygen under a laryngeal mask in a Mapleson D anesthesia system and under spontaneous breathing. Hydration was performed with 10 ml.kg-1 saline every hour. A thermal mattress was used. Precordial stethoscope, pulse oximetry and clinical parameters were used for monitoring. For euthanasia, ketamine 10 mg.kg-1 associated with potassium chloride 19.1% 1 ml.kg-1 was used intravenously. The average weight of the rabbits was 2721.25 ± 275.01 grams and the duration of the anesthetic procedure was 120 ± 87 minutes. Discussion. In long-term anesthesia, such as laparotomies, the use of pre-anesthetic medication and then anesthetic induction by the combination of agents is recommended. However, anesthetic management requires monitoring to prevent insufficient or excessive doses from occurring.

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Dilatation of Vascular Prostheses in Ascending Aortic Position: A Long-Term Follow-Up Computed Tomography Study with Comparison of Different Measurement Methods

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0036-1597116 ◽

2016 ◽

Vol 66 (03) ◽

pp. 206-214

Author(s):

Matthias Endlich ◽

Christian Krämer ◽

Chris Probst ◽

Armin Welz ◽

Kai Wilhelm ◽

...

Keyword(s):

Computed Tomography ◽

Measurement Methods ◽

Point Of View ◽

Cross Sectional ◽

Vascular Prostheses ◽

Aortic Replacement ◽

Ascending Aortic Replacement ◽

Long Term Follow Up ◽

Methods Of Measurement

Background The aim of this study was to evaluate long-term dilatation of Hemashield Gold and Hemashield Platinum vascular prostheses in ascending aortic position using different measurement methods to obtain precise results. Methods Between 1999 and 2007, 73 patients with Stanford type A dissection received ascending aortic replacement with Hemashield Gold and Hemashield Platinum prostheses. Measurements were performed using multiplanar reconstruction mode of electrocardiogram (ECG)-gated, multislice spiral computed tomography (MSCT) in strictly orthogonal cross-sectional planes. Different methods of measurement were compared and maximum dilatation was estimated for different time spans. Results Diameters calculated from the measured circumference showed a significant (p = 0.037) but clinically not relevant difference (0.1 mm) to the mean between the largest and the shortest cross-sectional diameter of the prosthesis. Dilatation after 24.2 ± 10.2 months was 8.5 ± 4.5%. Long-term dilatation after 91.8 ± 34 months amounted to 11.8 ± 4.2%. Conclusion Based on ECG-gated MSCT images, the presented methods of measurement provided reliable results. Long-term analysis shows low dilatation rates for Hemashield prostheses, which therefore can be considered as safe from this point of view. Nevertheless, a maximal dilatation of 20% could be relevant in valve sparing root replacement. It remains unclear if a dilatation like this contributes to the formation of suture aneurysms.

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Memory impairment induced by amphetamine derivatives in laboratory animals and in humans: a review

BioMolecular Concepts ◽

10.1515/bmc.2011.048 ◽

2012 ◽

Vol 3 (1) ◽

pp. 1-12 ◽

Cited By ~ 7

Author(s):

Jordi Camarasa ◽

Teresa Rodrigo ◽

David Pubill ◽

Elena Escubedo

Keyword(s):

Illicit Drugs ◽

Molecular Mechanisms ◽

Memory Performance ◽

Laboratory Animals ◽

Club Drugs ◽

Synthetic Drugs ◽

History Of ◽

Amphetamine Derivatives ◽

Considerable Body

AbstractThe 20th century brought with it the so-called club drugs (the most notorious being amphetamine derivatives), which are used by young adults at all-night dance parties. Methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA or ecstasy) are synthetic drugs with stimulant and psychoactive properties that belong to the amphetamine family. Here, we have reviewed the literature about the cognitive impairment induced by these two amphetamine derivatives and the preclinical and clinical outcomes. Although there is controversial evidence about the effect of methamphetamine and MDMA on learning and memory in laboratory animals, results from published papers demonstrate that amphetamines cause long-term impairment of cognitive functions. A large number of pharmacological receptors have been studied and screened as targets of amphetamine-induced cognitive dysfunction, and extensive research efforts have been invested to provide evidence about the molecular mechanisms behind these cognitive deficits. In humans, there is a considerable body of evidence indicating that methamphetamine and MDMA seriously disrupt memory and learning processes. Although an association between the impairments of memory performance and a history of recreational amphetamine ingestion has also been corroborated, a number of methodological difficulties continue to hamper research in this field, the most important being the concomitant use of other illicit drugs.

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Tissue ingrowth markedly reduces mechanical anisotropy and stiffness in fibre direction of highly aligned electrospun polyurethane scaffolds

10.1101/779942 ◽

2019 ◽

Cited By ~ 2

Author(s):

Hugo Krynauw ◽

Jannik Buescher ◽

Josepha Koehne ◽

Loes Verrijt ◽

Georges Limbert ◽

...

Keyword(s):

Elastic Modulus ◽

Vascular Graft ◽

Small Diameter ◽

Mechanical Anisotropy ◽

Fibre Direction ◽

Tissue Ingrowth ◽

Fibre Alignment ◽

Random Fibre ◽

Directed Research

AbstractPurposeThe lack of long-term patency of synthetic vascular grafts currently available on the market has directed research towards improving the performance of small diameter grafts. Improved radial compliance matching and tissue ingrowth into the graft scaffold are amongst the main goals for an ideal vascular graft.MethodsBiostable polyurethane scaffolds were manufactured by electrospinning and implanted in subcutaneous and circulatory positions in the rat for 7, 14 and 28 days. Scaffold morphology, tissue ingrowth, and mechanical properties of the scaffolds were assessed before implantation and after retrieval.ResultsTissue ingrowth after 24 days was 96.5 ± 2.3% in the subcutaneous implants and 77.8 ± 5.4% in the circulatory implants. Over the 24 days implantation, the elastic modulus at 12% strain decreased by 59% in direction of the fibre alignment whereas it increased by 1379% transverse to the fibre alignment of the highly aligned scaffold of the subcutaneous implants. The lesser aligned scaffold of the circulatory graft implants exhibited an increase of the elastic modulus at 12% strain by 77% in circumferential direction.ConclusionBased on the observations, it is proposed that the mechanism underlying the softening of the highly aligned scaffold in the predominant fibre direction is associated with scaffold compaction and local displacement of fibres by the newly formed tissue. The stiffening of the scaffold, observed transverse to highly aligned fibres and for more a random fibre distribution, represents the actual mechanical contribution of the tissue that developed in the scaffold.

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