Publications by authors named "M P L Parente"

193 Publications

Identification of ulcers and erosions by the novel Pillcam™ Crohn's Capsule using a convolutional neural network: a multicentre pilot study.

J Crohns Colitis 2021 Jul 6. Epub 2021 Jul 6.

Department of Gastroenterology, São João University Hospital, Alameda Professor Hernâni Monteiro, 4200-427, Porto, Portugal.

Background And Aims: Capsule endoscopy is a central element in the management of patients with suspected or known Crohn's disease. In 2017, PillCam™ Crohn's Capsule was introduced and demonstrated greater accuracy in the evaluation of extension of disease in these patients. Artificial Intelligence is expected to enhance the diagnostic accuracy of capsule endoscopy. This study aims to develop an AI algorithm for the automatic detection of ulcers and erosions of the small intestine and colon in PillCam™ Crohn's Capsule images.

Methods: A total of 8085 PillCam™ Crohn's Capsule images were extracted between 2017-2020, constituted by 2855 images of ulcers and 1975 erosions; the remaining images showed normal enteric and colonic mucosa. This pool of images was subsequently split into training and validation datasets. The performance of the network was subsequently assessed in an independent test set.

Results: The model had an overall sensitivity and specificity of 90.0% and 96.0%, respectively. The precision and accuracy of this model were 97.1% and 92.4%, respectively. Particularly, the algorithm detected ulcers with a sensitivity of 83% and specificity of 98%, and erosions with sensitivity and specificity of 91% and 93%, respectively.

Conclusion: A deep learning model capable of automatically detecting ulcers and erosions in PillCam™ Crohn's Capsule images was developed for the first time. These findings pave the way for the development of automatic systems for detection of clinically significant lesions, optimizing diagnostic performance and efficiency of monitoring Crohn's disease activity.
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http://dx.doi.org/10.1093/ecco-jcc/jjab117DOI Listing
July 2021

Mechanical Effects of a Maylard Scar During a Vaginal Birth After a Previous Caesarean.

Ann Biomed Eng 2021 Jun 10. Epub 2021 Jun 10.

INEGI - Institute of Science and Innovation in Mechanical and Industrial Engineering/DEMec, Faculty of Engineering, University of Porto, Porto, Portugal.

Caesarean section is one of the most common surgeries worldwide, even though there is no evidence supporting maternal and perinatal long-term benefits. Furthermore, the mechanical behavior of a caesarean scar during a vaginal birth after caesarean (VBAC) is not well understood since there are several questions regarding the uterine wound healing process. The aim of this study is to investigate the biomechanical Maylard fiber reorientation and stiffness influence during a VBAC through computational methods. A biomechanical model comprising a fetus and a uterus was developed, and a chemical-mechanical constitutive model that triggers uterine contractions was used, where some of the parameters were adjusted to account for the matrix and fiber stiffness increase in the caesarean scar. Several mechanical simulations were performed to analyze different scar fibers arrangements, considering different values for the respective matrix and fibers stiffness. The results revealed that a random fiber arrangement in the Maylard scar has a much higher impact on its mechanical behavior during a VBAC than the common fibers arrangement present in the uninjured uterine tissue. An increase of the matrix scar stiffness exhibits a lower impact, while an increase of the fiber's stiffness has no significant influence.
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http://dx.doi.org/10.1007/s10439-021-02805-zDOI Listing
June 2021

Multiple mineral horizons in layered outcrops at Mawrth Vallis, Mars, signify changing geochemical environments on early Mars.

Icarus 2020 May 17;341. Epub 2020 Jan 17.

Johns Hopkins University Applied Physics Lab, Laurel, MD, United States of America.

Refined calibrations of CRISM images are enabling identification of smaller deposits of unique aqueous materials on Mars that reveal changing environmental conditions at the region surrounding Mawrth Vallis. Through characterization of these clay-sulfate assemblages and their association with the layered, phyllosilicate units of this region, more details of the aqueous geochemical history can be gleaned. A stratigraphy including five distinct mineral horizons is mapped using compositional data from CRISM over CTX and HRSC imagery across 100s of km and from CRISM over HiRISE imagery across 100s of meters. Transitions in mineralogic units were characterized using visible/near-infrared (VNIR) spectral properties and surface morphology. We identified and characterized complex "doublet" type spectral signatures with two bands between 2.2 and 2.3 μm at one stratigraphic horizon. Based on comparisons with terrestrial sites, the spectral "doublet" unit described here may reflect the remnants of a salty, evaporative period that existed on Mars during the transition from formation of Fe-rich phyllosilicates to Al-rich phyllosilicates. Layered outcrops observed at Mawrth Vallis are thicker than in other altered regions of Mars, but may represent processes that were more widespread in wet regions of the planet during its early history. The aqueous geochemical environments supporting the outcrops observed here include: (i) the formation of Fe+-rich smectites in a warm and wet environment, (ii) overlain by a thin ferrous-bearing clay unit that could be associated with heating or reducing conditions, (iii) followed by a transition to salty and/or acidic alteration phases and sulfates (characterized by the spectral "doublet" shape) in an evaporative setting, (iv) formation of Al-rich phyllosilicates through pedogenesis or acid leaching, and (v) finally persistence of poorly crystalline aluminosilicates marking the end of the warm climate on early Mars. The "doublet" type units described here are likely composed of clay-sulfate assemblages formed in saline, acidic evaporative environments similar to those found in Western Australia and the Atacama desert. Despite the chemically extreme and variable waters present at these terrestrial, saline lake environments, active ecosystems are present; thus, these "doublet" type units may mark exciting areas for continued exploration important to astrobiology on Mars.
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http://dx.doi.org/10.1016/j.icarus.2020.113634DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152300PMC
May 2020

Marine algal flora of São Miguel Island, Azores.

Biodivers Data J 2021 16;9:e64969. Epub 2021 Apr 16.

CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Universidade dos Açores, Faculdade de Ciências e Tecnologia, Departamento de Biologia, 9500-321 Ponta Delgada, Açores, Portugal CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Universidade dos Açores, Faculdade de Ciências e Tecnologia, Departamento de Biologia 9500-321 Ponta Delgada, Açores Portugal.

Background: The macroalgal flora of the Island of São Miguel (eastern group of the Azores Archipelago) has attracted the interest of many researchers in the past, the first publications going back to the nineteenth century. Initial studies were mainly taxonomic, resulting in the publication of a checklist of the Azorean benthic marine algae. Later, the establishment of the University of the Azores on the Island permitted the logistic conditions to develop both temporal studies and long-term research and this resulted in a significant increase on research directed at the benthic marine algae and littoral communities of the Island and consequent publications.Prior to the present paper, the known macroalgal flora of São Miguel Island comprised around 260 species. Despite this richness, a significant amount of the research was never made public, notably Masters and PhD theses encompassing information regarding presence data recorded at littoral and sublittoral levels down to a depth of approximately 40 m around the Island and the many collections made, which resulted in vouchers deposited in the AZB Herbarium Ruy Telles Palhinha and the LSM- Molecular Systematics Laboratory at the Faculty of Sciences and Technology of the University of the Azores.The present publication lists the macroalgal taxonomic records, together with information on their ecology and occurrence around São Miguel Island, improving the knowledge of the Azorean macroalgal flora at local and regional scales.

New Information: A total of 12,781 specimens (including some identified only to genus) belonging to 431 taxa of macroalgae are registered, comprising 284 Rhodophyta, 59 Chlorophyta and 88 Ochrophyta (Phaeophyceae). Of these, 323 were identified to species level (212 Rhodophyta, 48 Chlorophyta and 63 Ochrophyta), of which 61 are new records for the Island (42 Rhodophyta, 9 Chlorophyta and 10 Ochrophyta), one an Azorean endemic (Predaea feldmannii subsp. azorica Gabriel), five are Macaronesian endemisms (the red algae Afonso-Carrillo, Sobrino, Tittley & Neto, Gil-Rodríguez & Haroun, (Seoane-Camba) S.M.Boo & J.M.Rico, P.Crouan & H.Crouan ex Karsakoff and the green alga O.C.Schmidt), 19 are introduced species (15 Rhodophyta, two Chlorophyta and two Ochrophyta) and 32 are of uncertain status (21 Rhodophyta, five Chlorophyta and six Ochrophyta).
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http://dx.doi.org/10.3897/BDJ.9.e64969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065013PMC
April 2021

Death-related factors in HIV/AIDS patients undergoing hemodialysis in an intensive care unit.

Rev Inst Med Trop Sao Paulo 2021 23;63:e33. Epub 2021 Apr 23.

Universidade Federal do Ceará, Faculdade de Medicina, Fortaleza, Ceará, Brazil.

HIV-infected patients are at high risk for developing critical diseases, including opportunistic infections (OI), with consequent admission in intensive care units (ICU). Renal disfunctions are risk factors for death in HIV/AIDS patients, and survival rates in patients undergoing hemodialysis are smaller than the ones observed in the general population. In this context, this study aimed to investigate death-related factors in HIV/AIDS patients in an intensive care setting. This is a retrospective cross-sectional study performed through the analysis of medical records from 271 HIV/AIDS-diagnosed patients hospitalized in an intensive care unit of an infectious disease hospital, in Fortaleza, Ceara State, Brazil. Patients were divided into two groups: those who underwent dialysis during hospitalization and those who did not. Clinical and demographic parameters that could be associated with death were evaluated. Results indicated a prevalence of death of 19.1% (CI 95%: 14.8-24.3). The median age of patients was 47 years, with a male predominance (71.3%). The main causes of admission were pulmonary tuberculosis (16.9%), followed by neurotoxoplasmosis (14.9%). In the bivariate analysis, for those that did not undergo dialysis, age, fever, dyspnea, oliguria, disorientation, kidney injury, use of lamivudine and efavirenz, length of hospitalization, CD4 count, WBC count, platelet count, urea, sodium and LDH levels were the associated variables. In those who needed dialysis, the use of stavudine, abacavir and ritonavir, and the length of hospitalization were associated factors. Renal toxicity by the antiretroviral agents and length of hospitalization increased the risk of death among HIV patients under dialysis.
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http://dx.doi.org/10.1590/S1678-9946202163033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8075620PMC
May 2021
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