Experimental procedures for the identification of material properties of intervertebal disc - a contribution for the development of biomimetic substitutes for the nucleus pulposus

Tese de Doutoramento em Engenharia Mecânica.The degenerative disc disease is among the promoters of low back pain, being normally associated with sciatica and disc herniation. Several experimental works have studied the intervertebral disc and proven that it presents poroelastic, osmotic, viscoelastic and anisotropic characteristics. However, the information about the mechanical loading on the IVD and its relation with the degenerative disc disease remains unclear. This work aimed to provide new insights about the mechanical properties of the intervertebral disc, as well as to contribute for selection and characterization of a new implant, developed by research partners at Nicast®, Lod, Israel. In order to better understand the biomechanical behavior of the intervertebral disc, a new set of experimental techniques for mechanical characterization, mechanical testing protocols and benchmark results that allows stablishing specifications for the new nucleus pulposus implants were addressed and performed. The experimental approach included mechanical tests in the overall structure of a porcine intervertebral disc: axial compressive tests at the motion segment (composed by the two adjacent vertebrae and the intervertebral disc) and annulus fibrosus level, as well as pressurization tests on nucleus pulposus. Moreover, it comprised several tests for the selection and mechanical characterization of the developed implant. The outcomes demonstrated that porcine motion segments are valid model to provide valuable information about the mechanical behavior of the human intervertebral disc, for the axial compressive tests. This study also proved that the rupture of the intervertebral disc could be reached at intradiscal pressure levels that are normally reported as physiological. Moreover, the compressive tests on the reinforced-ground matrix of the annulus fibrosus strengthened the idea, previous reported in the literature, that this structure presents an inhomogeneous behavior. Finally, the implant as revealed to have a satisfactory behavior under the set of experimental tests performed: while the ex-situ tests revealed promising characteristics in what concerns to the capacity to replace the nucleus pulposus, the stress relaxation tests in-situ, performed during the placement of the implants in the nuclear cavity of the motion segment, revealed no significant differences between the behavior of intact structures and the ones with the implants placed in the inner region of the intervertebral disc. The intervertebral disc is an intricate struture, with a “multi-factors dependent” biomechanical behavior, being extremely hard to design an efficient solution to replace its damaged structures. The experimental procedures of this work gave valuable information about the mechanical properties of the intervertebral disc, contributing for the advance of the knowledge on the biomechanics of its compounds. Furthermore, it helps to clarify the suitability of the new developed implant in the partial replacement of the damaged intervertebral disc.A doença degenerativa do disco intervertebral é uma das principais causas de dor lombar, estando intimamente associada à dor ciática e à herniação discal. Nos últimos anos têm sido realizados diversos trabalhos experimentais, os quais demonstraram que o disco apresenta características poro-elásticas, viscoelásticas e anisotrópicas. No entanto, a relação entre as cargas aplicadas no disco intervertebral e a degeneração do disco intervertebral não é clara. Este trabalho tem por objectivo providenciar informação relevante sobre as propriedades mecânicas do disco intervertebral, bem como contribuir para a seleção e caracterização de um novo implante, desenvolvido pela Nicast®, localizada em Lod, Israel - associado ao projeto no qual este trabalho se inseriu, o NP Mimetic. Para tal, no âmbito deste trabalho foram desenvolvidas e produzidas protocolos e técnicas experimentais para a caracterização mecânica e material, tendo sido obtidos valores standard importantes, que permitem, por um lado, o melhor conhecimento sobre o comportamento biomecânico do disco intervertebral, e por outro lado, definir as especificações relevantes para novos implantes de substituição do núcleo pulposo. A abordagem experimental incluiu testes mecânicos na estrutura do disco intervertebral de suínos, nomeadamente testes de compressão axial em unidades funcionais da coluna, constituídas por um disco intervertebral entre duas vértebras adjacentes, e no anel fibroso, bem como testes de pressurização na cavidade nuclear do disco. Além disso, este trabalho apresenta ainda diversos testes complementares para a seleção, caracterização e validação mecânica do implante desenvolvido. Os resultados obtidos demonstraram que as unidades funcionais da coluna de suínos apresentam-se como um modelo válido para a obtenção de informações relevantes sobre o comportamento mecânico do disco intervertebral humano, em testes de compressão. Este trabalho mostrou ainda que a rotura do disco intervertebral pode ser atingida para valores de pressão interna discal que são normalmente considerados como fisiológicos. No que diz respeito aos testes de compressão estática e dinâmica na matriz do anel fibroso, estes reforçaram a ideia previamente descrita na literatura, de que esta estrutura apresenta um comportamento não-homogéneo. Por último, os implantes apresentaram um comportamento muito satisfatório nos testes a que foram submetidos: enquanto os testes de avaliação do implante ex-situ revelaram características bastante promissoras no que concerne à capacidade de substituição do núcleo, os testes de relaxação de tensões in-situ, realizados aquando da colocação dos implantes na cavidade nuclear das unidades funcionais da coluna, revelaram a inexistência de diferenças significativas entre o comportamento dessas mesmas estruturas antes e após a colocação do implante na cavidade nuclear. O disco intervertebral é uma estrutura intrincada, apresentando um comportamento biomecânico de dependência multifactorial. Como tal, o desenvolvimento de implantes que possam substituir total ou parcialmente o disco intervertebral degenerado é uma tarefa de elevada complexidade. Este trabalho providencia um conjunto de dados relevantes sobre a resposta mecânica dos discos intervertebrais, contribuindo para o avanço do conhecimento do comportamento biomecânico dos seus componentes. Mais ainda, permite clarificar a adequabilidade de um novo implante na substituição do núcleo pulposo do disco intervertebral

A novel methodology to assess the relaxation rate of the intervertebral disc by increments on intradiscal pressure

Publicado em "Applied mechanics and materials, vol. 664 (2014) pp 379-383"The Intervertebral Disc (IVD) is subjected to several types of loading during daily routine events. However, the overloading on this structure induces higher Intradiscal Pressure (IDP), which could cause severe damage on its structure. This study describes a new approach to that allows monitorize and pressurize nuclear region of the IVD, with a cartilaginous endplate access, by the insertion of an external fluid, while a Motion Segment (MS-assembly composed by vertebra-disc-vertebra) is compressed at a physiological load. This methodology includes the use of a pneumatic structure that applies a certain pressure on the hydrostatic system, forcing a fluid to enter into the MS through a screw, with a drilled hollow along its entire length. Preliminary results indicated that this methodology presents high potential to efficiently pressurize the IVD, providing a useful tool to better understand the response of this structure under pressure.EC -European Commission(NMP-2009-SMALL-3-CP-FP 246351

A novel methodology for measurement of the intradiscal pressure and height disc variation of intervertebral disc under compression

The intervertebral disc (IVD) is subjected to several types of loading during daily routine events. However, the overloading on this structure induces higher intradiscal pressure (IDP), which could cause severe damage on its structure. This study describes a new approach to monitor IDP and determine the height disc variation by applying external pressure, while a motion segment (assembly composed by vertebra-disc-vertebra) compressed at a physiological load. This methodology includes the use of a pneumatic structure that applies a certain pressure on the hydrostatic system, forcing a fluid to enter into the motion segment, through a screw with a drilled hollow along its entire length with an internal bore. Preliminary results indicates these methodology presents high potential to efficiently pressurize the IVD, providing a useful tool to better understand the response of this structure under pressure

AVALIAÇÃO DE METAIS PESADOS NOS RECURSOS HÍDRICOS DO MUNICÍPIO DE BOQUIRA, NO SEMIÁRIDO BAIANO - BRASIL: Evaluation of heavy metals in water resources of the municipality of Boquira, in the semi-arid of Bahia - Brazil

The municipality of Boquira, located in the south central portion of the state of Bahia, is situated in a geological environment with important natural background for Pb and Zn, where it hosted between the years of 1960 and 1992 the largest mine of Pb and Zn of Brazil. The aim was to evaluate the quality of the water resources used for human consumption in the municipality, against possible natural and/or anthropic contamination by metals, and the influence of the environmental liabilities left in the municipality after the sudden abandonment of the mining. For this purpose, field campaigns and water aliquot sampling were carried out with the objective of performing laboratory chemical analysis for monitoring and comparison with other authors. It was concluded that there is influence of the natural background of the rocks of the municipality of Boquira on the water resources used by the population, given values ​​above the Maximum Allowable Value for human consumption for metals such as Ca, Mg, and Na. Although the highest concentrations for metals such as Pb, Zn and Cd were in the waters of the underground tailings and mine galleries, high levels of these metals were not found in the analyzed water resources.O município de Boquira, localizado na porção centro sul do estado da Bahia, está situado em um ambiente geológico com importante background natural para Pb e Zn, onde hospedou entre os anos de 1960 e 1992 a maior mina de Pb e Zn do Brasil. Diante disso, buscou-se avaliar a qualidade dos recursos hídricos utilizados para abastecimento humano no município, frente a uma possível contaminação natural e/ou antrópica por metais, e a influência dos passivos ambientais deixados no município após o súbito abandono da mineração. Para tanto, realizou-se campanhas de campo e amostragem de alíquotas de água objetivando a realização de análises químicas laboratoriais para monitoramento e comparação com outros autores. Concluiu-se que existe influência do background natural das rochas do município de Boquira nos recursos hídricos utilizados pela população, conferido valores acima do Valor Máximo Permitido para consumo humano para metais como Ca, Fe, Mg e Na. Apesar das maiores concentrações para metais como Pb, Zn e Cd estarem situadas nas águas das galerias da mina subterrânea e bacia de rejeito, não foi encontrado elevados teores desses metais nos recursos hídricos analisados

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

The intradiscal failure pressure on porcine lumbar intervertebral discs: an experimental approach

The intervertebral disc is submitted to complex loading during its normal daily activities which are responsible for variations of the hydrostatic pressure in its structure. Thus, the determination of the magnitude of failure hydrostatic pressure is essential as a potential for the evaluation of the mechanisms that promote the weakening and the disruption of the annular fibers, commonly linked to herniation process on the spine column. However, few studies include the determination of the failure pressure on discs and the results are widely contradictory. Therefore, the objective of the present work is to determine the values of IDP that promotes the disc disruption. To achieve this goal, the tests were performed using a hydraulic cylinder that inflates the intervertebral disc. The results revealed a mean pressure failure of 0.62 +/- 0.08MPa for lumbar porcine samples (n = 6). From this approach it can be concluded that (1) the potential for disc injury may exist at low pressures for lumbar porcine discs when compared several animal and human ones; (2) the rupture of human cervical and porcine lumbar annular fibers could occur for values of intradiscal pressure that are within the physiological range.This work was funded by the project "NP Mimetic - Biomimetic Nano-Fibre Based Nucleus Pulposus Regeneration for the Treatment of Degenerative Disc Disease", financed by the European Commission under FP7 (grant NMP-2009-SMALL-3-CP-FP 246351).info:eu-repo/semantics/publishedVersio

Quasi-static and dynamic properties of the intervertebral disc: experimental study and model parameter determination for the porcine lumbar motion segment

Purpose: The study of axial loading is essential to determine the properties of intervertebral disc. The objectives of this work are (1) to quantify the mechanical properties of porcine lumbar intervertebral discs under static and cyclic compressive loading, and (2) to determine the parameters of a five-parameter rheological model for porcine and compare them with those obtained for human lumbar intervertebral discs. Methods: Thus, the porcine lumbar motion segments were subjected to quasi-static and dynamic compression tests. The quasi-static tests were used to obtain the static stiffness coefficient at different strain rates, while the data from the cyclic compressive tests were used to both determine the dynamic stiffness coefficient and to be fitted in a 5-parameter model, in order to simulate the creep response of the porcine intervertebral discs. Results: The results demonstrated that dynamic stiffness coefficient of porcine discs is between four and ten times higher than the static stiffness coefficient, depending on load applied. The parameters of the rheological model suggested a low permeability of nucleus and endplate during the fast response of porcine discs. In addition, the fast response in terms of displacement is four times higher than those documented for human discs. Conclusions: This study revealed that care must be taken on the comparison between porcine and human discs, since they present different behaviour under quasi-static and dynamic compressive loading.This work was funded by the project "NP Mimetic-Biomimetic Nano-Fibre Based Nucleus Pulposus Regeneration for the Treatment of Degenerative Disc Disease", financed by the European Commission under FP7 (grant NMP-2009-SMALL-3-CP-FP 246351).info:eu-repo/semantics/publishedVersio

Comparison between the dynamic and initial creep response of porcine and human lumbar intervertebral discs

The study of mechanical properties of intervertebral disc (IVD) is important for the evaluation of disc implants. To determine these properties, several animal spine models were used. The goal of this work is to determine and compare the dynamic stiffness coefficient (K-d) and initial creep behavior of porcine intervertebral disc with the human ones. Porcine lumbar "motion segments" were subjected to 1200 cycles of axial compressive loading at 1 Hz, and a mean load of 500 N. The results were fitted with a mathematical model. The Kd values are in same magnitude as the previously reported for human. The model showed a good adjust to the initial creep behavior and the obtained parameters present the same magnitude as the human discs, with exception of time constant. This work revealed that porcine MS is an interesting model to study both the dynamic behavior and initial creep response of human disc.This work was performed within the project “NP Mimetic – Biomimetic Nano-Fibre Based Nucleus Pulposus Regeneration for the Treatment off Degenerative Disc Disease”, funded by the European Commission under FP7 (grant NMP-2009- SMALL-3-CP-FP 246351).info:eu-repo/semantics/publishedVersio

Potencial de propagação de cultivares de marmeleiro por estaquia Potencial of propagation of cultivars of quince for cuttings

Devido à escassez de trabalhos com o enraizamento de estacas de marmeleiro, realizou-se o presente trabalho com o objetivo de verificar o potencial de enraizamento de estacas de cultivares de marmeleiro. Utilizaram-se estacas lenhosas e lisas coletadas de plantas de marmeleiro 'Radiolo', 'Mendoza Inta-37', 'Much Prolife', 'Pineapple', 'Smyrna', 'De Patras', 'Provencia', 'Van Deman', 'Provance', 'Meliforme', 'Portugal' (Cydonia oblonga) e 'Japonês' (Chaenomelis sinensis L.), sendo estas padronizadas com 20 cm de comprimento. As estacas foram enterradas até a metade do comprimento em canteiro de terra e coberto por tela sombrite 50%, sendo umedecidas diariamente através de regas manuais. Após 75 dias, coletaram-se os seguintes dados biométricos: porcentagem de estacas enraizadas e brotadas, número de folhas e brotos, comprimento da maior raiz, comprimento médio das brotações e número de raízes emitidas por estaca. As cultivares Pineapple, De Patras, Provencia e Mendoza Inta-37 apresentaram maior potencialidade de propagação via estaquia.<br>Due to the shortage of works with the quince cutting, the present work was developed with the objective to verify the rooting potential of quince cultivars cutting. Hardwoody cuttings of quince were collected from 'Radiolo', 'Mendoza Inta-37', 'Much Prolife', 'Pineapple', 'Smyrna', 'De Patras', 'Provencia', 'Van Deman', 'Provance', 'Meliforme', 'Portugal' (Cydonia oblonga) and 'Japonês' (Chaenomelis sinensis L.), being these samples standardized with 20 cm of length. Soon after, half of the length of the cutting was put in a substrate constituted by soil and covered by sombrite 50%, being daily humidified by water. After 75 days, were evaluated the percentage of rooting and sprouting, number of leaves and sprouts, length of the largest root and sprouting and number of roots emitted by cutting. The cultivars Pineapple, De Patras, Provencia and Mendoza Inta-37 presented larger potentiality of propagation of cutting

Fungal planet description sheets: 625-715

Novel species of fungi described in this study include those from various countries as follows: Australia:Apiognomonia lasiopetali on Lasiopetalum sp Blastacervulus eucalyptorum on Eucalyptus adesmophloia,Bullanockia australis (incl. Bullanockia gen. nov.) on Kingia australis, Caliciopsis eucalypti on Eucalyptus marginata, Celerioriella petrophiles on Petrophile teretifolia, Coleophoma xanthosiae on Xanthosia rotundifolia, Coniothyrium hakeae on Hakea sp Diatrypella banksiae on Banksia formosa, Disculoides corymbiae on Corymbia calophylla, Elsinoë eelemani on Melaleuca alternifolia, Elsinoë eucalyptigena onEucalyptus kingsmillii, Elsinoë preissianae on Eucalyptus preissiana, Eucasphaeria rustici on Eucalyptus creta, Hyweljonesia queenslandica (incl. Hyweljonesia gen. nov.) on the cocoon of an unidentified microlepidoptera, Mycodiella eucalypti (incl. Mycodiella gen. nov.) on Eucalyptus diversicolor,Myrtapenidiella sporadicae on Eucalyptus sporadica, Neocrinula xanthorrhoeae (incl. Neocrinula gen. nov.) on Xanthorrhoea sp, Ophiocordyceps nooreniae on dead ant, Phaeosphaeriopsis agavacearum on Agavesp, Phlogicylindrium mokarei on Eucalyptus sp, Phyllosticta acaciigena on Acacia suaveolens,Pleurophoma acaciae on Acacia glaucoptera, Pyrenochaeta hakeae on Hakea sp, Readeriella lehmannii onEucalyptus lehmannii, Saccharata banksiae on Banksia grandis, Saccharata daviesiae on Daviesia pachyphylla, Saccharata eucalyptorum on Eucalyptus bigalerita, Saccharata hakeae on Hakea baxteri,Saccharata hakeicola on Hakea victoria, Saccharata lambertiae on Lambertia ericifolia, Saccharata petrophiles on Petrophile sp, Saccharata petrophilicola on Petrophile fastigiata, Sphaerellopsis hakeae onHakea sp, and Teichospora kingiae on Kingia australis. Brazil: Adautomilanezia caesalpiniae (incl. Adautomilanezia gen. nov.) on Caesalpina echinata, Arthrophiala arthrospora (incl. Arthrophiala gen. nov.) on Sagittaria montevidensis, Diaporthe caatingaensis (endophyte from Tacinga inamoena), Geastrum ishikawae on sandy soil, Geastrum pusillipilosum on soil, Gymnopus pygmaeus on dead leaves and sticks,Inonotus hymenonitens on decayed angiosperm trunk, Pyricularia urashimae on Urochloa brizantha, andSynnemellisia aurantia on Passiflora edulis. Chile: Tubulicrinis australis on Lophosoria quadripinnata.France: Cercophora squamulosa from submerged wood, and Scedosporium cereisporum from fluids of a wastewater treatment plant. Hawaii: Beltraniella acaciae, Dactylaria acaciae, Rhexodenticula acaciae,Rubikia evansii and Torula acaciae (all on Acacia koa). India: Lepidoderma echinosporum on dead semi-woody stems, and Rhodocybe rubrobrunnea from soil. Iran: Talaromyces kabodanensis from hypersaline soil.La Réunion: Neocordana musarum from leaves of Musa sp. Malaysia: Anungitea eucalyptigena onEucalyptus grandis × pellita, Camptomeriphila leucaenae (incl. Camptomeriphila gen. nov.) on Leucaena leucocephala, Castanediella communis on Eucalyptus pellita, Eucalyptostroma eucalypti (incl.Eucalyptostroma gen. nov.) on Eucalyptus pellita, Melanconiella syzygii on Syzygium sp, Mycophilomyces periconiae (incl. Mycophilomyces gen. nov.) as hyperparasite on Periconia on leaves of Albizia falcataria,Synnemadiella eucalypti (incl. Synnemadiella gen. nov.) on Eucalyptus pellita, and Teichospora nephelii onNephelium lappaceum. Mexico: Aspergillus bicephalus from soil. New Zealand: Aplosporella sophorae onSophora microphylla, Libertasomyces platani on Platanus sp, Neothyronectria sophorae (incl.Neothyronectria gen. nov.) on Sophora microphylla, Parastagonospora phoenicicola on Phoenix canariensis, Phaeoacremonium pseudopanacis on Pseudopanax crassifolius, Phlyctema phoenicis onPhoenix canariensis, and Pseudoascochyta novae-zelandiae on Cordyline australis. Panama: Chalara panamensis from needle litter of Pinus cf. caribaea. South Africa: Exophiala eucalypti on leaves ofEucalyptus sp, Fantasmomyces hyalinus (incl. Fantasmomyces gen. nov.) on Acacia exuvialis,Paracladophialophora carceris (incl. Paracladophialophora gen. nov.) on Aloe sp, and Umthunziomyces hagahagensis (incl. Umthunziomyces gen. nov.) on Mimusops caffra. Spain: Clavaria griseobrunnea on bare ground in Pteridium aquilinum field, Cyathus ibericus on small fallen branches of Pinus halepensis, Gyroporus pseudolacteus in humus of Pinus pinaster, and Pseudoascochyta pratensis (incl. Pseudoascochyta gen. nov.) from soil. Thailand: Neoascochyta adenii on Adenium obesum, and Ochroconis capsici on Capsicum annuum. UK: Fusicolla melogrammae from dead stromata of Melogramma campylosporum on bark ofCarpinus betulus. Uruguay: Myrmecridium pulvericola from house dust. USA: Neoscolecobasidium agapanthi (incl. Neoscolecobasidium gen. nov.) on Agapanthus sp, Polyscytalum purgamentum on leaf litter,Pseudopithomyces diversisporus from human toenail, Saksenaea trapezispora from knee wound of a soldier, and Sirococcus quercus from Quercus sp. Morphological and culture characteristics along with DNA barcodes are provided. © 2017 Naturalis Biodiversity Center & Westerdijk Fungal Biodiversity Institute