Thermal analysis in drilling of ex vivo bovine bones

Bone drilling is a common procedure in Medicine, mainly in traumatology and orthopedic procedure for fractures fixation and in reconstructive surgery. The success of this surgical procedure is dependent on many factors, namely, on heat generation control during the bone drilling. The main concern in bone drilling is the mechanical and thermal damage of the bone induced by inappropriate parameters such as drill speed and feed-rate during the drilling. This study focuses on the temperature generated during drilling of cortical bone tissue (bovine origin) and solid rigid polyurethane foams with similar mechanical properties to the human bone tissue. Different parameters such as drill speed, feed-rate and hole depth were tested. All results showed that improvement of the drilling parameters and the drill temperatures can be estimated. It was concluded that when the drill speed and feed-rate were higher, the bone temperature increase was lower. The obtained results of temperature in the drilling process of polyurethane foam blocks or bovine bone were compared with a good agreement in between both. © 2017 World Scientific Publishing Company.This research was supported by the Portuguese Foundation of Science and Technology under research project UID/EMS/50022/2013.info:eu-repo/semantics/publishedVersio

The heat transfer modelling for bone metastatic lesion minimization using two different cement types

Bone tumors grow when cells divide without any control, forming a tissue mass. Bone tumors could be benign or malignant, and primary or metastatic due to systemic cancer cells dissemination. They destroy bone and lead to pathological fractures. The main objective of this work is to study the thermal effect induced by the bone cement polymerization, in the bone metastatic tumor minimization. To assess the clinical effect, it is important to test this methodology before its application and obtain sustained results. In this work, a numerical model was developed to predict the temperature distribution produced by cement polymerization. Thus, distinct tests were produced for different two cements types and amounts introduced in a cortical and spongy bone metastatic lesion, with or without an intramedullary titanium nail. The bone cement was introduced to fill in a metastatic lytic lesion area, which the main objective is playing a promising role for bone tumor necrosis due to thermal effects and biomechanical stabilization for function and pain relief.info:eu-repo/semantics/publishedVersio

Numerical thermal study in bone tumor lesion

With the evolution of science and new diagnostic technologies, it was possible to observe a continuous improvement in the treatments in general and in the aid of the patients' quality of life. Malignant tumors can be primary or secondary (metastases), with abnormal growth of cells able to invade other types of tissues and organs through systemic dissemination. Sarcomas are rare primary malignancies formed from mesenchymal tissue and often located at the extremities. In this work, the main objective is to evaluate the minimization of the evolution of bone tumor lesion through the injection of bone cement, filling in the space of the lytic tumor lesion. This methodology allows to verify at the adjacent cement – bone tissue interface, an increase in temperature that can control the local growth of bone metastasis. Different computational models, obtained by medical image processing, will be carried out for two analyses (patient younger than 70 years and older than 70 years). The computational model allows a transient thermal analysis using the finite element method. The temperature results may determine the thermal necrosis effect in the bone tumor lesion. Results will be compared using three different bone cements.info:eu-repo/semantics/publishedVersio

Bioelectricity generation using long-term operated biocathode: RFLP based microbial diversity analysis

FRH/BPD/33864/2009 UIDB/50006/2020 UIDP/50006/2020In the present work, power generation and substrate removal efficiencies of long-term operated microbial fuel cells, containing abiotic cathodes and biocathodes, were evaluated for 220 days. Among the two microbial fuel cell (MFC) types, the one containing biocathode showed higher power density (54 mW/m2), current density (122 mA/m2) coulombic efficiency (33%), and substrate removal efficiency (94%) than the abiotic cathode containing MFC. Voltammetric analysis also witnessed higher and sustainable electron discharge for the MFC with biocathode, when compared with the abiotic cathode MFC. Over the tested period, both MFC have shown a cell voltage drop, after 150 and 165, days, for the MFC with biocathode and abiotic cathodes, respectively. Polymerase chain reaction (PCR) based restriction fragment length polymorphism (RFLP) analysis identified 281 clones. Bacteria belonging to Acinetobacter, Acidovorax, Pseudomonas and Burkholderia were observed in the abiotic cathode MFC. Bacteria belonging to Geobacter, Cupriavidus and Acidobacteria were observed in the biocathode MFC. Almost similar types of archaea (Methanosarcinales, Methanolinea, Nitrososphaera and Methanomicrobiales) were observed in both MFCs.publishersversionpublishe

The Potential of Unsaturated Polyesters in Biomedicine and Tissue Engineering: Synthesis, Structure-Properties Relationships and Additive Manufacturing

The success of Tissue Engineering (TE) based approaches is strongly dependent on the development of novel biomaterials for the design of 3D matrices with tailored biomechanical properties to promote the regeneration of human tissues and organs.This review covers the critical aspects related with the preparation of new unsaturated polyester (UP) resin formulations with suitable biological, chemical, thermal and morphological properties for the additive manufacturing (AM) of TE constructs. In this context, the basic principles of available AM technologies, with a special focus on novel stereolithography processes such as microstereolithography (micro-SLA), stereo-thermal-lithography (STLA), two-photon polymerization (TPP) and nanostereolithography (nano-SLA), are also presented and discussed. Ultimately, the present review will provide a better insight into the limitations and potential of combining UP and AM towards the rationale design/fabrication of complex artificial tissue substitute

Effect of drill speed on the strain distribution during drilling of bovine and human bones

Drilling is an operation commonly required in orthopaedic surgery for insertion of screws and internal fixation of bone fractures. Induced damage is one of the undesired effects of drilling mainly due to the use of inadequate drilling parameters. During the recent years, scientists have been trying to describe the relationship between drilling parameters and bone injury. However, no studies have examined the level of strain generated in the bone during the drilling process. This paper focuses on the analysis of different drill speeds during drilling of fresh bovine femora and human cadaveric tibiae. The main contribution of this work is to determine how differences in applied drill speeds affect the strain of cortical tissue near the drilling site and the drill bit temperature. Strains were measured in ex-vivo material during the osteotomy preparation with three drill speeds (520, 900 and 1370 r.p.m.). Additionally, a thermographic camera was used to measure the drill bit temperature. As the drilling operations are blind in nature with unknown depth, the osteotomies were performed using a drill press machine without control of the feed rate or depth. Drill bit geometry was kept constant with 4 mm of diameter, point angle 120⁰ and helix angle 30⁰. The tests were conducted at room temperature without applying cooling at the drilling zone. Bone strains near to the drilling sites were recorded with high accuracy using linear strain gages mounted around the diaphyseal cortex. It was noted that the bone strain and drill bit temperature increased with an increasing drill speed. Human and bovine bone samples presented significantly different levels of strain and temperature. Both strain and temperature were higher when drilling bovine femora than when drilling human cadaveric tibiae

Surface functionalization of cuttlefish bone-derived biphasic calcium phosphate scaffolds with polymeric coatings

Cuttlefish bone (CB) has been explored as biomaterial in the bone tissue-engineering field due to its unique porous structure and capacity of the aragonite mineral to be hydrothermally converted into calcium phosphates (CaPs). In the present study, undoped and ion (Sr2+, Mg2+ and/or Zn2+) doped biphasic calcium phosphate (BCP) scaffolds were prepared by hydrothermal transformation (HT, 200 °C, 24 h) of CB. The obtained scaffolds were sintered and then coated with two commercial polymers, poly(ε-caprolactone) (PCL) or poly(DL-lactide) (PDLA), and with two synthesized ones, a poly(ester amide) (PEA) or a poly(ester urea) (PEU) in order to improve their compressive strength. The scaffolds were characterized by X-ray diffraction (XRD) coupled with structural Rietveld refinement, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results demonstrate that CB could be entirely transformed into BCPs in the presence or absence of doping elements. The initial CB structure was preserved and the polymeric coatings did not jeopardize the interconnected porous structure. Furthermore, the polymeric coatings enhanced the compressive strength of the scaffolds. The in vitro bio-mineralization upon immersing the scaffolds into simulated body fluid (SBF) demonstrated the formation of bone-like apatite surface layers in both uncoated and coated scaffolds. Overall, the produced scaffolds exhibit promising properties for bone tissue engineering applications.publishe

Influence of human t-cell lymphotropic virus type 1 (HTLV-1) Infection on laboratory parameters of patients with chronic hepatitis C virus

Hepatitis C virus (HCV) and human T-cell lymphotropic virus type 1 (HTLV-1) share routes of transmission and some individuals have dual infection. Although some studies point to a worse prognosis of hepatitis C virus in patients co-infected with HTLV-1, the interaction between these two infections is poorly understood. This study evaluated the influence of HTLV-1 infection on laboratory parameters in chronic HCV patients. Twelve HTLV-1/HCV-coinfected patients were compared to 23 patients infected only with HCV, in regard to demographic data, risk factors for viral acquisition, HCV genotype, presence of cirrhosis, T CD4+ and CD8+ cell counts and liver function tests. There was no difference in regard to age, gender, alcohol consumption, smoking habits, HCV genotype or presence of cirrhosis between the groups. Intravenous drug use was the most common risk factor among individuals co-infected with HTLV-1. These patients showed higher TCD8+ counts (p = 0.0159) and significantly lower median values of AST and ALT (p = 0.0437 and 0.0159, respectively). In conclusion, we have shown that HCV/HTLV-1 co-infected patients differs in laboratorial parameters involving both liver and immunological patterns. The meaning of these interactions in the natural history of these infections is a matter that deserves further studies.O vírus da hepatite C (VHC) e vírus linfotrópico humano tipo 1 (HTLV-1) compartilham formas de transmissão e algumas pessoas apresentam coinfecção. Embora alguns estudos apontem para um pior prognóstico da infecção pelo VHC em pacientes coinfectados com HTLV-1, a interação entre estas infecções é mal compreendida. Este estudo avaliou a influência da infecção pelo HTLV-1 em parâmetros laboratoriais de pacientes com VHC. 12 coinfectados VHC/HTLV-1 foram comparados com 23 pacientes monoinfectados com VHC, no que diz respeito aos dados demográficos, fatores de risco para aquisição viral, genótipo do VHC, presença de cirrose, contagens de linfócitos T CD4+ e CD8+ e testes de função hepática. Não houve diferença em relação à idade, sexo, consumo de álcool, tabagismo, genótipo do VHC ou presença de cirrose entre os grupos. O uso de drogas injetáveis foi o fator de risco mais comum entre coinfectados. Esses pacientes apresentaram maiores contagens de linfócitos T CD8+ e valores medianos de AST e ALT significativamente mais baixos (p = 0,0437 e 0,0159, respectivamente). Em conclusão, demonstrou-se que os pacientes com VHC/HTLV-1 diferem quanto aos parâmetros hepáticos e imunológicos. O significado destas diferenças na história natural destas infecções é um assunto que merece estudos mais aprofundados

Personalized dynamic phantom of the right and left ventricles based on patient-specific anatomy for echocardiography studies — Preliminary results

Dynamic phantoms of the heart are becoming a reality, with their use spread across both medical and research fields. Their purpose is to mimic the cardiac anatomy, as well as its motion. This work aims to create a dynamic, ultrasound-compatible, realistic and flexible phantom of the left and right ventricles, with application in the diagnosis, planning, treatment and training in the cardiovascular field for studies using echocardiography. Here, we focus on its design and production with polyvinyl alcohol cryogel (PVA-C), to be assembled with a pump and an electromechanical (E/M) system in a water tank. Based on a patient-specific anatomical model and produced using a 3D printing technique and molding, the PVA-C phantom mimics the ventricles' natural anatomy and material properties, while the pump and E/M systems mimic the natural movements and pressures. The PVA-C phantom was assessed by imaging and measuring it using a four-dimensional ultrasound machine. The PVA-C phantom demonstrated to be a versatile option to produce patient-specific biventricular models, preserving their shape after manufacturing and presenting good echogenic properties. Both chambers were clearly seen in the ultrasound images, together with the interventricular septum and the myocardial wall. Automated left ventricle measures revealed a decrease of its volume with regard to the designed model (98 ml to 74 ml). Overall, the preliminary results are satisfactory and encourage its use for the abovementioned purposesFEDER funds through the Competitiveness Factors Operational Programme (COMPETE), and by National funds through the Foundation for Science and Technology (FCT) under the project POCI -01-0145-FEDER-007038 and EXPL/BBB-BMD/2473/2013, and by the projects NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-024300, supported by the NORTE 2020, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). J. Gomes-Fonseca, P. Morais, S. Queirós, and F. Veloso were funded by FCT under the Ph.D. grants PD/BDE/113597/2015, SFRH/BD/95438/2013, SFRH/BD/93443/2013, and SFRH/BD/131545/2017info:eu-repo/semantics/publishedVersio

A Preliminary Study of Microbial Water Quality Related to Food Safety in Recirculating Aquaponic Fish and Vegetable Production Systems

This study examines microbial water quality in recirculating aquaponic systems. The pathogens studied were E. coli and Salmonella, and the levels were compared with existing food safety standards