A study of chemically treated pericardia to manufacture the leaflets of percutaneous heart valves : biomechanical analyses and modelisation

Contexte: En raison de l'utilisation répandue des valvules cardiaques aortiques prothétiques, il est extrêmement important d'en étudier la biofonctionnalité, la biodurabilité et la biocompatibilité. Les valves mécaniques ont une excellente durabilité. Cependant, en raison des traitements anticoagulants, il existe des risques de thromboembolique et hémorragique. Les valves polymériques ont une faible résistance à la calcification et à la thrombose. À cet égard, les valves biologiques sont préférables. Plus récemment, les chirurgiens et les cardiologues ont développe à l'implantation de valves aortiques percutanées, plutôt qu’à la chirurgie ouverte pour traiter les patients âgés et fragiles. Cependant, la durabilité des bioprothèses soulève toujours des questions reliées au sertissage et l’expansion lors de l'implantation. Comme la performance des bioprothèses dépend de l'architecture et du comportement mécanique du tissu sélectionné, il est nécessaire de sélectionner le tissu le plus approprié pour fabriquer ces prothèses. Objectifs: Il s’agit d’identifier le tissu le plus approprié avec la plus longue durabilité pour fabriquer des valvules cardiaques en comparant les propriétés mécaniques et histologiques des péricardes équin, porcin et d’âne par rapport à celles du péricarde bovin et des feuillets de la valve aortique humaine. Hypothèse: La durabilité des valves cardiaques bioprothétiques est largement déterminée par les caractéristiques histologiques et mécaniques des tissus des feuillets. Par conséquent, la sélection du péricarde selon sa structure histologique et ses propriétés mécaniques permettra d’augmenter la durée de vie de ces prothèses. Méthodologie: 1. Étude des structures de collagène des tissus sélectionnés. 2. Étude des propriétés mécaniques des tissus et évaluation de leur durabilité avec différents tests mécaniques. 3. Extraction des propriétés hyperélastiques et viscoélastiques biaxiales à l'aide des modèles appropriés. 4. Application du modèles d'éléments finis est appliqué en utilisant les propriétés mécaniques extraites pour évaluer la déhiscence possible de la valve et le stress sous la charge physiologique. Résultats: Le péricarde d’âne et le péricarde équin ont démontré une architecture ondulée de faisceaux de collagène semblable à celle du péricarde bovin. L’architecture ondulée du péricarde peut convenir aux valves aortiques transcutanées car elles sont moins susceptibles d'être délaminées lors du sertissage. Selon des tests mécaniques, les pourcentages de relaxation des différents péricardes équin (16%), âne (28%) et bovin (21%) étaient supérieurs à ceux du péricarde porcin (11%) et similaires aux feuillets valvulaires aortiques humains natifs (21%). En particulier, le péricarde porcin a démontré un comportement plus rigide (module d'élasticité plus élevé), basé sur sa plus grande amplitude d'énergie de déformation et la pente moyenne des courbes contrainte-étirement. Ce tissu était également moins extensible que les deux autres péricardes et les feuillets humains, en raison de sa souche aréale inférieure. En général, les propriétés mécaniques du péricarde d’âne sont plus proches des feuillets valvulaires humains. De plus, le modèle âne n'a induit que des régions localisées à faible stress pendant les phases systolique et diastolique du cycle cardiaque. En outre, une diminution des contraintes mécaniques sur les feuillets bioprothétiques devrait contribuer à réduire la dégénérescence des tissus et augmenter la durabilité à long terme de la valve. Conclusion: D'après nos observations, les spécimens péricardiques se sont comportés comme des tissus anisotropes et non linéaires - bien caractérisés par des modèles constitutifs. Les résultats indiquent que le péricarde d'âne est mécaniquement et histologiquement plus approprié pour la fabrication de prothèses valvulaires cardiaques que le péricarde bovin. Les résultats de cette étude peuvent être utilisés dans la conception et la fabrication de valvules cardiaques bioprothétiques percutanéei.Background: Due to the widespread use of prosthetic aortic heart valves, investigating these prostheses in terms of biofunctionality, biodurability and biocompatibility is of considerable importance. Mechanical heart valves (MHVs) have excellent durability; however, due to the long-term use of anticoagulants, thromboembolism and hemorrhage remain a possibility. Polymeric valves have a low resistance to calcification and thromboembolism. In this respect, biological valves are preferred. In recent years, surgeons and cardiologists have also used transcatheter aortic valve implantation (TAVI) due to its superiority over the open-heart surgery to treat elderly and frail patients. However, the long-term durability of the commercially available bioprosthesesstill raises questions related to crimping and ballooning at the implantation. The function and performance of the bioprostheses depend on the collagen architecture and mechanical behaviors of the pericardial tissue. Therefore, it is necessary to select the most appropriate pericardia to manufacture these prostheses. Objectives: To identify the most appropriate tissue with a long durability to make bioprosthetic heart valves by analyzing the mechanical and histological properties of the equine, porcine, and donkey pericardia, with respect to those of the bovine pericardium and human aortic valve leaflets. Hypothesis: The long term durability of bioprosthetic heart valves is largely determined by the leaflet tissues. Consequently, selecting the pericardium based on its adequate mechanical property and histological structure will increase the lifetime of these prostheses. Methodologies: 1. Histological analysis was performed to investigate the collagen structures of the selected tissues. 2. Different mechanical tests (uniaxial tests, biaxial tests, and stress relaxation tests) were performed to determine the mechanical properties of the tissues and to evaluate their durability. 3. The biaxial hyperelastic and viscoelastic properties of the selected tissues were extracted using the appropriate models. 4. The finite element model was applied using the extracted mechanical properties to evaluate valve dehiscence and stress under physiological loadings. Results: The donkey and equine pericardia showed a wavy collagen bundle architecture similar to the bovine pericardium. The wavy pericardia may be suitable for the transcatheter aortic valves (TAVs) because they are less likely to be delaminated during crimping. According to the mechanical tests, the relaxation percentages of the equine (16%), donkey (28%), and bovine (21%) pericardia were greater than that of the porcine (11%) pericardium and similar to that of the native human aortic valve leaflets (21%). In particular, the porcine pericardium exhibited a stiffer behavior (higher elastic modulus), based on its greater strain energy magnitude and the average slope of stress-stretch curves. This tissue was also less distensible than the other two pericardia and the native leaflets, due to its lower areal strain. In general, among the pericardia analyzed, the mechanical properties of the donkey pericardium are closer to that of the native leaflets. Furthermore, the donkey model showed low stress regions during the systolic and diastolic phases of the cardiac cycle. Such decreased mechanical stress in the bioprosthetic leaflets should reduce tissue degeneration and increase the long-term durability of the valve. Conclusion: Based on the observations, the pericardial specimens behaved as anisotropic and nonlinear tissues, and their mechanical behaviors were very well characterized by the constitutive models. The results indicate that, compared to the bovine pericardium, the donkey pericardium is mechanically and histologically more appropriate to manufacture heart valve prostheses. Therefore, this study contributes to our understanding of the difference in animal pericardia with respect to human heart leaflets, which is very useful for the design and manufacture of the percutaneous bioprosthetic heart valves

Homestead Neighborhood and the Oregon Health Sciences University Background and Recommendations Report

The Homestead Neighborhood is located in southwest Portland. It was first studied as part of the Marquam Hill Plan in 1977. Since that time two major health providers, the Shriners and the Veterans Administration,have built new facilities on the hill. The Oregon Health Sciences University is now poised and ready for major expansion of its medical schools, hospital and research facilities. Meanwhile, area residents and property owners, have voiced concerns about increased traffic, and building density. Oregon Health Sciences University (OHSU) contracted with the School of Urban and Public Affairs at Portland State University to draft a comprehensive neighborhood plan, to supplement its own long rang planning on Marquam Hill. Graduate students in the Masters in Urban Planning (MUP) program, under the direction of Michael S. Harrison AICP, Chief Planner for the City of Portland, prepared this plan over a ten week time period. This plan will also be presented to the Homestead Neighborhood Association to provide a basis for further studies. The recommendations presented in the following section, are solely those of the students in the USP 528 Comprehensive Planning Workshop. As presented here, they represent many rounds of in-class discussion, fieldwork and input from residents.The Advisory Committee contributed review and advice. The document makes reference to several sites. The medical complex is considered the Oregon Health Sciences University, the Shriners Hospital and the Veterans Administration Hospital. The campus refers to the same area as the medical complex. The Homestead Plat refers to the residential and commercial area just west of the campus up to SW 14thStreet. The Homestead neighborhood is a political jurisdiction recognized by the City of Portland which surrounds the areas platted as Homestead on Marquam Hill, but also embraces parts of Portland Heights and the Hillsdale area. Marquam Hill is a geographical term which relates to a much wider area than just the Homestead neighborhood. The background section covers the history, characteristics and patterns of land use in the Homestead Neighborhood. It provides a factual basis for determining alternatives,making recommendations and establishing policy. It also may be used as a general reference.The background is organized into seven sections: historical perspective; sumary of planning activities; overview of transportation patterns; analysis of development and infrastructure; discussions of amenities and topography; and an overview of demographics. A comprehensive property inventory detailing individual parcel ownership and physical characteristics has also been compiled and included as an addenda to this report. The fourth section of the report describes and analyzes the planning methodology used to research this project. Property data was collected and tabulated using Multnomah County records which were then checked and enhanced through field observation. Citizen participation was fostered by impanelling an advisory committee consisting of neighborhood representatives of the neighborhood, medical complex and the City Park Bureau, conducting a workshop with the neighborhood and distributing surveys to all residences. The findings of the class are presented in the final section of this report. The findings and recommendations contained in this report are solely those of the class and do not necessarily represent the policies of the City of Portland, Portland State University, Oregon Health Sciences University or the Homestead Neighborhood Association. The report will hopefully foster communication between the Homestead Neighborhood Association, the medical complex and the City of Portland. This is not intended as a final plan but rather as a starting point for further discussion. The next step in this planning process is for the Neighborhood and University to continue a dialog to formulate the goals and objectives of a neighborhood plan. A series of public discussions would follow to determine the contents of the final document. The final step would be to get the plan ratified by the Portland City Council

The comparison of LC50 of clove essence and MS222 in Acipenser persicus, Oncorhynchus mykiss and Cyprinus carpio

The LC50 of two anaesthetic agents, clove essence and MS222, on the cultivated fish species, Acipenser persicus, Oncorhynchus mykiss, Cyprinus curpio were estimated. 640 samples of above mentioned species were used exposing anaesthetic agents for 2 minutes.LC50 of clove essence and MS222 for sturgeon estimated 297 and 291 ppm, for common carp was 271 and 272 ppm; and for rainbow trout Was 199 and 207 pmm, respectively. Significant difference was found only between LC50 of MS222 in rainbow trout with LC50 of both agents in two other species. Also, the results showed that there is no significant difference on poisoning of two applied drugs in all above mentioned species; with comparing different species, rainbow trout had lower tolerance to both anesthetics

Studies of the differential effects of pre- and postnatal tri-iodothyronine (T3) and thyroxine (T4) deficiency on the cellular development of rat neocortex Using unbiased design-based stereological methods

SIGLEAvailable from British Library Document Supply Centre- DSC:DX96412 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Les monnaies hellénistiques et kouchanes des fouilles franco-afghanes de Bactres (Balkh, Afghanistan)

Summary -This paper deals with the Hellenistic and Kushan coins (3rd ca BCE-4th ca CE) found in the French-Afghan excavations of Bactra (Balkh, Afghanistan), i. e. 113 coins in total. The distribution pattern of the coins of Euthydemus I (ca 230-190 BCE) as well as the Yuezhi imitations of Heliocles I (2nd-1st c. BCE) in the Oxus valley is considered in detail, based on numismatic data from recent archaeological excavations in Central Asia. These new data contribute to a better understanding of Bactra’s place in the numismatic landscape during the aforementioned periods.Cet article s’intéresse aux monnaies des périodes hellénistique et kouchane (IIIe siècle av. J.-C.-IVe siècle apr. J.-C.) en provenance des fouilles franco-afghanes de Bactres (Balkh, Afghanistan), dont 113 exemplaires ont été identifiés. La répartition des monnaies d’Euthydème I (230-190 av. J.-C.) et celle des imitations Yuezhi d’Hélioclès I (IIe-Ier siècles av. J.-C.) dans la vallée de l’Oxus font l’objet d’études particulières, à partir des données numismatiques livrées par les fouilles récentes en Asie centrale. Ces nouvelles données permettent d’approfondir notre connaissance de la place de Bactres dans le paysage numismatique aux périodes étudiées.Bordeaux Olivier, BESENVAL Roland, Marquis Philippe, Rassoli Nader. Les monnaies hellénistiques et kouchanes des fouilles franco-afghanes de Bactres (Balkh, Afghanistan). In: Revue numismatique, 6e série - Tome 176, année 2019 pp. 15-46

Effect of hydro-alcoholic extract of Proveskia abrotanoides on blood glucose and liver enzymes level in streptozotocin-induced diabetic rats

Background and Objective: Diabetes mellitus is a metabolic disorder that is characterized by hyperglycemia resulting from defects in insulin secretion and action, or even both of them. Proveskia abrotanoides has anti-bacterial, anti-parasitic, antioxidant, anti-inflammatory, and analgesic effects. This study was done to evaluate the effect of hydro-alcoholic extract of Proveskia abrotanoides on blood glucose and liver enzymes level in streptozotocin-induced diabetic rats. Methods: In this experimental study, 60 male Wistar rats were randomly allocated into including healthy control, healthy received Glibenclamide, healthy -treated with 150, 300 and 600 mg/kg/bw of Proveskia abrotanoides extract, diabetic control, diabetic treated with 150, 300 and 600 mg/kg/bw of extract, positive control (diabetic treated with the Glibenclamide). After the treatments, the blood samples were taken from the animals and the level of blood glucose and liver enzymes including ALT, AST, and ALP were measured. Finally, the effect of hydro-alcoholic extract of Proveskia abrotanoides was compared with Glibenclamide as a conventional drug. Results: The results showed a significant increase in liver enzymes (ALT, AST, ALP) in hyperglycemic rats compared to the healthy controls (P<0.05). The mean of AST, ALT and ALP enzymes in hyperglycmia group were 286.83±7.46, 172.16±5.74, 526.17±8017, respectively while in healthy control it was 239±12.16, 100±2.42 and 196.33±6.82, respectively. In hyperglycemic rats treatment with doses of 150, 300, and 600 significantly reduced liver enzymes levels in compare to hyperglycemic contol group (P<0.05). In group treated with 150 mg/kg/bw, the average of ALP, AST, and ALT enzymes was 160.67±6.29, 127.33±5.23 and 260.33±7.18, respectively. The mean of ALP, AST, and ALT enzymes in group treated with 300 mg/ kg/bw was 197.5±6.71, 144.33±8.82 and 201.67±9.60, respectively. In group treated with 600 mg/kg/bw, the mean of ALP, AST, and ALT enzymes was 192.23±8.23, 111.17±6.13 and 329±7.43, respectively. The hydro-alcoholic extract of Proveskia abrotanoides significantly reduced serum glucose and liver enzymes in comparison with Glibenclamide group (P<0.05). Conclusion: The hydro-alcoholic extract of Proveskia abrotanoides reduces liver enzymes and blood glucose level in streptozotocin-induced diabetic rats

Les monnaies hellénistiques et kouchanes des fouilles franco-afghanes de Bactres (Balkh, Afghanistan)

International audienceCet article s’intéresse aux monnaies des périodes hellénistique et kouchane (IIIe siècle av. J.-C.-IVe siècle apr. J.-C.) en provenance des fouilles franco-afghanes de Bactres (Balkh, Afghanistan), dont 113 exemplaires ont été identifiés. La répartition des monnaies d’Euthydème I (230-190 av. J.-C.) et celle des imitations Yuezhi d’Hélioclès I (IIe-Ier siècles av. J.-C.) dans la vallée de l’Oxus font l’objet d’études particulières, à partir des données numismatiques livrées par les fouilles récentes en Asie centrale. Ces nouvelles données permettent d’approfondir notre connaissance de la place de Bactres dans le paysage numismatique aux périodes étudiées