Radon-domain detection of the nipple and the pectoral muscle in mammograms

In this paper, methods are presented for automatic detection of the nipple and the pectoral muscle edge in mammograms via image processing in the Radon domain. Radon-domain information was used for the detection of straight-line candidates with high gradient. The longest straight-line candidate was used to identify the pectoral muscle edge. The nipple was detected as the convergence point of breast tissue components, indicated by the largest response in the Radon domain. Percentages of false-positive (FP) and false-negative (FN) areas were determined by comparing the areas of the pectoral muscle regions delimited manually by a radiologist and by the proposed method applied to 540 mediolateral-oblique (MLO) mammographic images. The average FP and FN were 8.99% and 9.13%, respectively. In the detection of the nipple, an average error of 7.4 mm was obtained with reference to the nipple as identified by a radiologist on 1,080 mammographic images (540 MLO and 540 craniocaudal views).

Human Alveolar Bone-Derived Cell-Culture Behaviour on Biodegradable Poly(L-lactic Acid)

Poly(L-lactic acid) (PLA) is a polymer of great technological interest, whose excellent mechanical properties, thermal plasticity and bioresorbability render it potentially useful for environmental applications, as a biodegradable plastic and as a biocompatible material in biomedicine. The interactions between an implant material surface and host cells play central roles in the integration, biological performance and clinical success of implanted biomedical devices. Osteoblasts from human alveolar bone were chosen to investigate the cell behaviour when in contact with PLA discs. Cell morphology and adhesion through osteopontin (OPN) and fibronectin (FN) expression were evaluated in the initial osteogenesis, as well as cell proliferation, alkaline phosphatase activity and bone nodule formation. It was shown that the polymer favoured cell attachment. Cell proliferation increased until 21 days but in a smaller rate when compared to the control group. On the other hand, ALP activity and bone mineralization were not enhanced by the polymer. It is suggested that this polymer favours cell adhesion in the early osteogenesis in vitro, but it does not enhance differentiation and mineralization. (C) Koninklijke Brill NV, Leiden, 2009

The rheology of flotation froths

A literature review has highlighted the need to measure flotation froth rheology in order to fully characterise the role of the froth in the flotation process. The initial investigation using a coaxial cylinder viscometer for froth rheology measurement led to the development of a new device employing a vane measuring head. The modified rheometer was used in industrial scale flotation tests at Mt. Isa Copper Concentrator. The measured froth rheograms show a non-Newtonian nature for the flotation froths (pseudoplastic flow). The evidence of the non-Newtonian flow has questioned the validity of application of the Laplace equation in froth motion modelling as used by a number of researchers, since the assumption of irrotational flow is violated. Correlations between the froth rheology and the froth retention time, water hold-up in the froth and concentrate grades have been found. These correlations are independent of air flow rate (test data at various air flow rates fall on one similar trend line). This implies that froth rheology may be used as a lumped parameter for other operating variables in flotation modelling and scale up. (C) 2003 Elsevier Science B.V. All rights reserved.

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls

Background: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. Aim: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). Subjects and methods: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. Results: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). Conclusion: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference

Parathyroid hormone venous sampling prior to reoperation for primary hyperparathyroidism

Background: The surgical cure rate for primary hyperparathyroidism is greater than 95%. For those who have recurrent or persistent disease, preoperative localization improves reoperation success rates. Selective parathyroid venous sampling (SPVS) for intact parathyroid hormone is particularly useful when non-invasive localization techniques are negative or inconclusive. Methods: We present all known cases (n = 13) between 1994 and 2002 who had venous sampling for localization at our institution prior to reoperation for recurrent or persistent primary hyperparathyroidism. Comparison was made with non-invasive localization procedures. Results of invasive and non-invasive localization were correlated with surgical findings. Results: Of the nine reoperated cases, eight had positive correlations between SPVS and operative findings and histopathology. SPVS did not reveal the parathyroid hormone source in one case with negative non-invasive localization procedures. Comparisons between SPVS, computerized tomography (CT), and parathyroid scintigraphy (MIBI) as expressed in terms of true positive (TP), false positive (FP) and false negative (FN) were: SPVS - TP 88.8%, FP 0%, FN 11.1%; CT - TP 22.2%, FP 22.2%, FN 55.5%; and MIBI - TP 33.3%, FP 0%, FN 66.6%. At least seven of the nine operated cases have been cured; another remained normocalcaemic 2 weeks after subtotal parathyroidectomy. Conclusion: In our institution SPVS has proven to be a valuable tool in cases with recurrent or persistent primary hyperparathyroidism and negative non-invasive localization procedures.

SAR calculation using FDTD simulations

The main intend of this work, is to determinate the Specific Absorption Rate (SAR) on human head tissues exposed to radiation caused by sources of 900 and 1800MHz, since those are the typical frequencies for mobile communications systems nowadays. In order to determinate the SAR, has been used the FDTD (Finite Difference Time Domain), which is a numeric method in time domain, obtained from the Maxwell equations in differential mode. In order to do this, a computational model from the human head in two dimensions made with cells of the smallest possible size was implemented, respecting the limits from computational processing. It was possible to verify the very good efficiency of the FDTD method in the resolution of those types of problems.

Pre-operative tractography of the facial nerve in vestibular schwannomas: inter-observer agreement with surgical findings

Pre-operative diffusion tensor (DT) tractography is currently employed in our institutions. We use it to predict the course of the facial nerve (FN) in the vicinity of vestibular schwannomas (VS) of the cerebellopontine angle (CPA). In this study we were interested to assess the inter-observer reproducibility of this method. Two Neuroradiologists (PMGP and TT) determined independently the location of the FN by tractography and compared the results with in-vivo findings of microsurgery of VS.

Influence of crystallite size of nanophased hydroxyapatite on fibronectin and osteonectin adsorption and on MC3T3-E1 osteoblast adhesion and morphology

The characteristic topographical features (crystallite dimensions, surface morphology and roughness) of bioceramics may influence the adsorption of proteins relevant to bone regeneration. This work aims at analyzing the influence of two distinct nanophased hydroxyapatite (HA) ceramics, HA725 and HA1000 on fibronectin (FN) and osteonectin (ON) adsorption and MC3T3-E1 osteoblast adhesion and morphology. Both substrates were obtained using the same hydroxyapatite nanocrystals aggregates and applying the sintering temperatures of 725ºC and 1000ºC, respectively. The two proteins used in this work, FN as an adhesive glycoprotein and ON as a counter-adhesive protein, are known to be involved in the early stages of osteogenesis (cell adhesion, mobility and proliferation). The properties of the nanoHA substrates had an important role in the adsorption behavior of the two studied proteins and clearly affected the MC3T3- E1 morphology, distribution and metabolic activity. HA1000 surfaces presenting slightly larger grain size, higher root-mean-square roughness (Rq), lower surface area and porosity, allowed for higher amounts of both proteins adsorbed. These substrates also revealed increased number of exposed FN cell-binding domains as well as higher affinity for osteonectin. Regarding the osteoblast adhesion results, improved viability and cell number were found for HA1000 surfaces as compared to HA725 ones, independently of the presence or type of adsorbed protein. Therefore the osteoblast adhesion and metabolic activity seemed to be more sensitive to surfaces morphology and roughness than to the type of adsorbed proteins.

PET/CT com 18-fluor-fluorodeoxiglucose no seguimento do melanoma maligno cutâneo

Introdução – O melanoma maligno cutâneo (MMC) é considerado uma das mais letais neoplasias e no seu seguimento recorre-se, para além dos exames clínicos e da análise de marcadores tumorais, a diversos métodos imagiológicos, como é o exame Tomografia por Emissão de Positrões/Tomografia Computorizada (PET/CT, do acrónimo inglês Positron Emission Tomography/Computed Tomography) com 18fluor-fluorodeoxiglucose (18F-FDG). O presente estudo tem como objetivo avaliar a utilidade da PET/CT relativamente à análise da extensão e à suspeita de recidiva do MMC, comparando os achados imagiológicos com os descritos em estudos CT. Metodologia – Estudo retrospetivo de 62 estudos PET/CT realizados em 50 pacientes diagnosticados com MMC. Excluiu-se um estudo cujo resultado era duvidoso (nódulo pulmonar). As informações relativas aos resultados dos estudos anatomopatológicos e dos exames imagiológicos foram obtidas através da história clínica e dos relatórios médicos dos estudos CT e PET/CT. Foi criada uma base de dados com os dados recolhidos através do software Excel e foi efetuada uma análise estatística descritiva. Resultados – Dos estudos PET/CT analisados, 31 foram considerados verdadeiros positivos (VP), 28 verdadeiros negativos (VN), um falso positivo (FP) e um falso negativo (FN). A sensibilidade, especificidade, o valor preditivo positivo (VPP), o valor preditivo negativo (VPN) e a exatidão da PET/CT para o estadiamento e avaliação de suspeita de recidiva no MMC são, respetivamente, 96,9%, 96,6%, 96,9%, 96,6% e 96,7%. Dos resultados da CT considerados na análise estatística, 14 corresponderam a VP, 12 a VN, três a FP e cinco a FN. A sensibilidade, especificidade, o VPP e o VPN e a exatidão da CT para o estadiamento e avaliação de suspeita de recidiva no MMC são, respetivamente, 73,7%, 80,0%, 82,4%, 70,6% e 76,5%. Comparativamente aos resultados CT, a PET/CT permitiu uma mudança na atitude terapêutica em 23% dos estudos. Conclusão – A PET/CT é um exame útil na avaliação do MMC, caracterizando-se por uma maior acuidade diagnóstica no estadiamento e na avaliação de suspeita de recidiva do MMC comparativamente à CT isoladamente.

Fasceíte Necrotizante Pós-Apendicite Aguda

A Fasceíte Necrotizante (FN) é um processo infeccioso da fascia profunda, de evolução rápida e progressiva com necrose secundária do tecido celular subcutâneo. Os autores apresentam um caso de FN da parede abdominal, como complicação extremamente rara de apendicite aguda. Trata-se de uma criança, apendicectomizada por apendicite aguda gangrenada, que evolui para quadro infeccioso grave, com dor e processo inflamatório da parede abdominal. Após diagnóstico, foi submetido a desbridamento cirúrgico da parede abdominal e drenagem de abcesso intraperitoneal. Realizada terapêutica antibiótica, desbridamentos cirúrgicos e pensos sucessivos da lesão e ao 22º dia efectuou-se enxerto dermo-epidérmico de área cruenta residual da parede abdominal. Porque o prognóstico está intimamente relacionado com o tempo decorrido até ao diagnóstico correcto e início de terapêutica adequada, é de extrema importância que este diagnóstico seja considerado.

Fasceite Necrosante e Otite Média Aguda

A fasceíte necrosante (FN) é uma doença rara em pediatria. Na maior parte dos casos surge como complicação de varicela, sendo a pele habitualmente a porta de entrada e o Streptococcus pyogenes o agente mais frequente. Os autores descrevem um caso clínico de uma criança de 8 anos, previamente saudável que, no contexto de uma otite média aguda medicada com um anti-inflamatório não esteróide (AINE), desenvolve uma infecção invasiva a Streptococcus 13 hemoliticus do grupo A.

Estudo Comparativo entre Dois Tipos de Eco-Contrastes: Echovist® e Levovist®, Avaliação da Permeabilidade Tubária em Infertilidade Feminina

Na propedêutica inicial do casal infértil, a realização da Sonossalpingografia (SoSG) contrastada através de dois tipos de ecocontrastes, Echovist® e Levovist®, durante a realização da ultra-sonografia ginecológica convencional pode, em casos seleccionados, substituir como exame de “screening” da permeabilidade tubária a Histerossalpingografia (HSG) e a Laparoscopia com cromotubação (LPC). Objectivos: Comparar os resultados da permeabilidade tubária através da SoSG contrastada com Echovist® ou com Levovist® e a HSG e determinar a sua acuidade em relação a LPC considerada “gold-standard”. Pacientes e métodos: Foram avaliadas prospectivamente 90 pacientes inférteis submetidas a SoSG em que se utilizou o contraste ecogénico Echovist® e 28 pacientes em que se utilizou o eco-realçador Levovist®. Para a HSG utilizou-se, em todas as pacientes, contraste iodado e hidrossolúvel Telebrix®. A observação da permeabilidade tubária teve sua avaliação final e sistemática pela LPC. Resultados: No estudo das trompas pelo Echovist® observamos permeabilidade em 67 pacientes (74,4%) e obstruções bilaterais em 23 das pacientes (25,6%) e pelo Levovist®, respectivamente, 22 (78,6%) e 6 pacientes (21,4%). Na comparação da avaliação da permeabilidade tubária entre a SoSG com Echovist® e LPC encontramos: especificidade € 91,3%, sensibilidade (S) 100%, falsos positivos (FP) 8,7%, falsos negativos (FN) 0%, valor preditivo positivo (VPP) 97,1%, valor preditivo negativo (VPN) 100% e Kappa de 96,5%, e entre a HSG e LPC, neste grupo Echovist® foram: E 100%, S 91,04%, FP 0%, FN 8,96%, VPP 100%, VPN 79,31% e Kappa de 88,6%. Na comparação da avaliação da permeabilidade tubária entre a SoSG com Levovist® e LPC encontramos: E 100%, S 100%, FP 0%, FN 0%, VPP 100%, VPN 100% e Kappa de 100%, e entre a HSG e LPC, no grupo Levovist® foram: E 100%, S 86,36%, FP 0%, FN 13,64%, VPP 100%, VPN 66,67% e Kappa de 82,2%. Conclusões: As Sonossalpingografias (SoSG) contrastadas utilizando-se como eco-realçadores o Echovist® ou o Levovist® podem ser consideradas exames complementares equivalentes na rotina da avaliação inicial do factor tubário por apresentarem, além do mesmo composto químico activo, alta sensibilidade, especificidade e concordância, ambos com acuidade superior à HSG quando comparados com a LPC.

Biochemical and physical surface functionalization of polycaprolactone as a key mediator of osteogenic differentiation and vascularized tissue morphogenesis

Tese de Doutoramento em Engenharia de Tecidos, Medicina Regenerativa e Células Estaminais.

Avaliação de indicadores de qualidade do solo sob alternativas de recuperação do solo no Nordeste Paraense

Os indicadores convencionais de fertilidade de solo, mais comumente utilizados, enfatizam o balanço ácido-base e o conteúdo de elementos químicos, mas não consideram adequadamente as propriedades biológicas do solo, responsáveis por grande parte do seu funcionamento. Os indicadores biológicos, ainda pouco difundidos, levam em consideração a atividade microbiana do solo que é mais sensível à dinâmica do solo. Em Marapanim-PA, e utilizando um desenho experimental inteiramente casualizado, com quatro repetições, avaliou-se o comportamento dos indicadores do solo carbono e nitrogênio da biomassa microbiana, fosfatase ácida, matéria orgânica, carbono orgânico e fósforo disponível, em um solo com cultivo sequencial de mandioca e milho, preparo com corte-e-trituração da capoeira original. Os fatores corte-e-trituração, fosfato natural e adubação verde foram arranjados nos seguintes tratamentos: capoeira; testemunha; fosfato natural (FN); feijão-de-porco [Canavalia ensiformis (L.) DC] (FP); FN + FP; FN + guandu [Cajanus cajan (L.) Millspaugh]. (G); FN + titônia [Tithonia diversifolia (Hemsley) A. Gray] (T); FP + G; FP + T. Em quatro épocas de amostragens, foram tiradas amostras compostas do solo (0 - 10 cm) de cada parcela para análise dos indicadores. Os indicadores estudados foram influenciados pela época de amostragem do solo. Os indicadores fosfatase ácida, nitrogênio da biomassa microbiana e carbono da biomassa microbiana foram capazes de detectar os efeitos de maior número de tratamentos de recuperação do solo testados, enquanto a matéria orgânica do solo foi o menos capaz. Ao longo do tempo, a resposta dos indicadores variou em função dos fatores estudados.

Regulation of human mesenchymal stem cell osteogenesis by specific surface density of fibronectin: a gradient study

 The success of synthetic bone implants requires good interface between the material and the host tissue. To study the biological relevance of fi bronectin (FN) density on the osteogenic commitment of human bone marrow mesenchymal stem cells (hBMMSCs), human FN was adsorbed in a linear density gradient on the surface of PCL. The evolution of the osteogenic markers alkaline phosphatase and collagen 1 alpha 1 was monitored by immunohistochemistry, and the cytoskeletal organization and the cell-derived FN were assessed. The functional analysis of the gradient revealed that the lower FN-density elicited stronger osteogenic expression and higher cytoskeleton spreading, hallmarks of the stem cell commitment to the osteoblastic lineage. The identifi cation of the optimal FN density regime for the osteogenic commitment of hBM-MSCs presents a simple and versatile strategy to signifi cantly enhance the surface properties of polycaprolactone as a paradigm for other synthetic polymers intended for bone-related applications.