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347 results on '"P, Vassilakos"'

3. Self-supervised learning-based cervical cytology for the triage of HPV-positive women in resource-limited settings and low-data regime

Author

Stegmüller, Thomas, Abbet, Christian, Bozorgtabar, Behzad, Clarke, Holly, Petignat, Patrick, Vassilakos, Pierre, and Thiran, Jean-Philippe

Subjects
Electrical Engineering and Systems Science - Image and Video Processing, Computer Science - Computer Vision and Pattern Recognition
Abstract

Screening Papanicolaou test samples has proven to be highly effective in reducing cervical cancer-related mortality. However, the lack of trained cytopathologists hinders its widespread implementation in low-resource settings. Deep learning-based telecytology diagnosis emerges as an appealing alternative, but it requires the collection of large annotated training datasets, which is costly and time-consuming. In this paper, we demonstrate that the abundance of unlabeled images that can be extracted from Pap smear test whole slide images presents a fertile ground for self-supervised learning methods, yielding performance improvements relative to readily available pre-trained models for various downstream tasks. In particular, we propose \textbf{C}ervical \textbf{C}ell \textbf{C}opy-\textbf{P}asting ($\texttt{C}^{3}\texttt{P}$) as an effective augmentation method, which enables knowledge transfer from open-source and labeled single-cell datasets to unlabeled tiles. Not only does $\texttt{C}^{3}\texttt{P}$ outperforms naive transfer from single-cell images, but we also demonstrate its advantageous integration into multiple instance learning methods. Importantly, all our experiments are conducted on our introduced \textit{in-house} dataset comprising liquid-based cytology Pap smear images obtained using low-cost technologies. This aligns with our objective of leveraging deep learning-based telecytology for diagnosis in low-resource settings.

Published
2023

7. Functional muscle hypertrophy by increased insulin‐like growth factor 1 does not require dysferlin

Author

Barton, Elisabeth R, Pham, Jennifer, Brisson, Becky K, Park, SooHyun, Smith, Lucas R, Liu, Min, Tian, Zuozhen, Hammers, David W, Vassilakos, Georgios, and Sweeney, H Lee

Subjects
Medical Physiology, Biomedical and Clinical Sciences, Clinical Sciences, Brain Disorders, Intellectual and Developmental Disabilities (IDD), Muscular Dystrophy, Rare Diseases, Musculoskeletal, Animals, Diaphragm, Dysferlin, Insulin-Like Growth Factor I, Mice, Mice, Knockout, Mice, Transgenic, Muscle, Skeletal, Muscular Dystrophies, Organ Size, dysferlin, insulin-like growth factor 1, Miyoshi myopathy, muscle hypertrophy, skeletal muscle function, Medical and Health Sciences, Neurology & Neurosurgery, Biological sciences, Biomedical and clinical sciences
Abstract

IntroductionDysferlin loss-of-function mutations cause muscular dystrophy, accompanied by impaired membrane repair and muscle weakness. Growth promoting strategies including insulin-like growth factor 1 (IGF-1) could provide benefit but may cause strength loss or be ineffective. The objective of this study was to determine whether locally increased IGF-1 promotes functional muscle hypertrophy in dysferlin-null (Dysf-/- ) mice.MethodsMuscle-specific transgenic expression and postnatal viral delivery of Igf1 were used in Dysf-/- and control mice. Increased IGF-1 levels were confirmed by enzyme-linked immunosorbent assay. Testing for skeletal muscle mass and function was performed in male and female mice.ResultsMuscle hypertrophy occurred in response to increased IGF-1 in mice with and without dysferlin. Male mice showed a more robust response compared with females. Increased IGF-1 did not cause loss of force per cross-sectional area in Dysf-/- muscles.DiscussionWe conclude that increased local IGF-1 promotes functional hypertrophy when dysferlin is absent and reestablishes IGF-1 as a potential therapeutic for dysferlinopathies.

Published
2019

19. A Phenomenological Study of the Lived Experiences of it and Cybersecurity Professionals in Botswana: Investigating the Perceived Leadership Effect on Supply Chain Cybersecurity

Author

Vassilakos, Andreas and Martin, Ronald

Abstract

This qualitative study aimed to investigate the experiences of cybersecurity professionals in the context of supply chain cybersecurity in a developing nation. Sixteen professionals from various industries in Botswana were interviewed. The study found that despite the critical role of cybersecurity as an organizational resource, it was still undervalued and underdeveloped, and leadership lacked comprehension of its importance. The participants expressed concerns about the increasing cybersecurity threats, lack of reporting, and technological inadequacies. The study recommends that organizations should develop a comprehensive cybersecurity strategy that includes policies, procedures, technical controls, vendor management, employee awareness and education, regular risk assessments, and incident response plans. The authors also proposed further research steps on supply chain cybersecurity for developing nations. The study contributes to the literature on supply chain cybersecurity in the context of developing nations and provides practical recommendations for organizations to enhance their cybersecurity measures.

Published
2023
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25. Telecytologic diagnosis of cervical smears for triage of self-sampled human papillomavirus–positive women in a resource-limited setting: concept development before implementation.

Author

Vassilakos, Pierre, Clarke, Holly, Murtas, Micol, Stegmüller, Thomas, Wisniak, Ania, Akhoundova, Farida, Sando, Zacharie, Orock, George Enow, Sormani, Jessica, Thiran, Jean-Philippe, and Petignat, Patrick

Abstract

Cytology is an option for triaging human papillomavirus (HPV)-positive women. The interpretation of cytologic slides requires expertise and financial resources that are not always available in resource-limited settings. A solution could be offered by manual preparation and digitization of slides on site for real-time remote cytologic diagnosis by specialists. In the present study, we evaluated the operational feasibility and cost of manual preparation and digitization of thin-layer slides and the diagnostic accuracy of screening with virtual microscopy. Operational feasibility was evaluated on 30 cervical samples obtained during colposcopy. The simplicity of the process and cellularity and quality of digitized thin-layer slides were evaluated. The diagnostic accuracy of digital versus glass slides to detect cervical intraepithelial neoplasia grade 2 or worse was assessed using a cohort of 264 HPV-positive Cameroonian women aged 30 to 49 years. The histologic results served as the reference standard. Manual preparation was found to be feasible and economically viable. The quality characteristics of the digital slides were satisfactory, and the mean cellularity was 6078 squamous cells per slide. When using the atypical squamous cells of undetermined significance or worse threshold for positivity, the diagnostic performance of screening digital slides was not significantly different statistically compared with the same set of slides screened using a light microscope (P = 0.26). We have developed an innovative triage concept for HPV-positive women. A quality-ensured telecytologic diagnosis could be an effective solution in areas with a shortage of specialists, applying a same day "test-triage-treat" approach. Our results warrant further on-site clinical validation in a large prospective screening trial. • Telecytology may be a feasible method of triaging HPV-positive women in low-resource settings. • The manual preparation of slides and their digitization is simple and low cost. • Accuracy of digital screening does not differ from light microscopy screening when ≥ASC-US. • Digital screening by remote specialists could be used in a one visit test-triage-treat approach. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Understanding the Challenge of Cybersecurity in Africa: A Holistic Analysis of Southern African Development Community (SADC) and Foundation for Future Research

Author

Vassilakos, Andreas and Martin, Ronald

Abstract

The continuous shift towards a world relying on computing leads to an increase of the potential risk factors that users face while roaming the digital world. The constant technological innovation we are witnessing creates the necessity of developing reliable systems, strategies, and frameworks against nefarious users threatening the security of information and data. Emerging countries begin to face issues related to cyber warfare and security. This study provides insight into the technological risk factors that could potentially delay further development in the technological growth of developing nations, focusing on selected countries in the African continent. The threats against confidentiality, integrity, and availability do not have an impact exclusively on information systems but, to a larger scale, on a region’s efforts for innovation. This paper intends to provide the readers a holistic review of the status of cyber security in the context of developing countries, specifically in the African continent and the Southern African Development Community.

Published
2023
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47. A cross-sectional study exploring triage of human papillomavirus (HPV)-positive women by visual assessment, manual and computer-interpreted cytology, and HPV-16/18-45 genotyping in Cameroon.

Author

Vassilakos, Pierre, Wisniak, Ania, Catarino, Rosa, Foguem, Eveline Tincho, Balli, Christine, Saiji, Essia, Tille, Jean-Christophe, Kenfack, Bruno, and Petignat, Patrick

Subjects
CERVICAL intraepithelial neoplasia, CYTOLOGY, CROSS-sectional method, MEDICAL triage, PAPILLOMAVIRUSES
Abstract

Background High-risk human papillomavirus (HPV)-positive women require triage to identify those at higher risk of cervical intraepithelial neoplasia grade 2 or worse (CIN2+). We aimed to compare visual assessment of the cervix, manual cytology and automated cytology as triage tests to screen HPV-positive women, and to assess over-treatment rates after visual assessment and over-referral rates to colposcopy after cytology. Methods The present cross-sectional study is nested in a large prospective screening trial in Cameroon. Evaluations of the tests have been conducted individually and in combination with HPV-16/HPV-18/45 genotyping. For the evaluation of over-treatment and colposcopic over-referral, we simulated two screening scenarios: (1) one-visit scenario (test-triage-and-treatment); and (2) two-visit scenario (test-triage-and-colposcopy). Results 1582 women with a median age of 40 years (IQR 35-45) performed self-sampling for HPV testing, of which 294 (18.6%) were HPV-positive, and 12.2% had CIN2+. Sensitivities for CIN2+ detection were 77.1% for visual assessment, 80.0% for manual cytology, and 84.8% for automated cytology. Sensitivity of combined tests was higher compared with single tests. The highest sensitivity was obtained by the combination of genotyping and automated cytology (91.2%). In the one-visit scenario, the over-treatment rate was 83.9% in referred women, with a ratio of 6.2 treated women per CIN2+. In the two-visit scenario, the lowest over-referral rate would have been under manual cytology (45.0%), with a ratio of 1.8 referred women per CIN2+. Single and combined triage strategies by automated cytology gave rise to over-referral rates of 69.2% and 76.7%, respectively, and a ratio of 3.2 and 4.3 referred women per CIN2+, respectively. Discussion Triage of HPV-positive women using a combination of genotyping and automated cytology for CIN2+ detection may provide public benefits in low- and middle-income countries. [ABSTRACT FROM AUTHOR]

Published
2021
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48. Illicit Activities Beneath the Surface Web: Investigating Domestic Extremism on Anonymous Social Media Platforms

Author

Dawson, Maurice, Vassilakos, Andreas, Remy, Jose Luis Castanon, and Setor, Tenace Kwaku

Abstract

At the beginning of 2021, the Internet was used to spread words to incite insurrection and violence through social media, incited a pro-Trump mob riot into a U.S. Capitol building. Furthermore, due to recent acts of domestic terrorism in Texas, New Zealand, and California, police authorities have begun investigating social media presence that premeditated harmful acts. In all three instances, the shooters posted their manifesto online and had a presence on 8chan. The common thread among all shooters is their identification as a white nationalist and their social media site affiliation with Infinitechan, where they hid their radical ideas. Similarities in the shooters’ profiles include their perceived viewpoints of population groups regarding their political, ethnic, and social identities. This paper will provide insight into the forums where domestic terrorists spread their agendas. It will also set the foundation for further research towards a strategic algorithm that compiles and analyses relevant users’ profiles by using OSINT and data analytics techniques).

Published
2021
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49. Understanding the Challenge of Cybersecurity in Critical Infrastructure Sectors

Author

Dawson, Maurice, Bacius, Robert, Gouveia, Luis Borges, and Vassilakos, Andreas

Abstract

The cybersecurity of critical infrastructures is an essential topic within national and international security as 16 critical infrastructure sectors touch various aspects of American society. Because the failure to provide adequate cybersecurity controls within the critical infrastructure sectors renders the country open to an attack that could have a debilitating effect on security, national public health, safety, and economic security, this matter is so vital that there is the Presidential Policy Directive (PPD) 21 Critical Infrastructure Security and Resilience advances a national policy to strengthen and maintain secure, functioning and resilient critical infrastructure. An organization identified as the Cybersecurity and Infrastructure Security Agency (CISA) at the Department of Homeland Security (DHS) has the mission to be the risk advisor for the United States (US). Other organizations, such as the National Security Agency (NSA), have approved a specific Knowledge Unit (KU) to address cybersecurity for critical infrastructures associated with doctoral-level granting programs. To address this challenge, it is necessary to identify threats better and defend against them while mitigating risks to an acceptable level. Only then can a nation build a more secure and resilient infrastructure for the future while defending against present-day bad actors as cyberwarfare, cyber espionage, and cybersecurity attacks are the modern-day threats that need to be addressed in planning, designing, implementation, and maintenance. Therefore, the researchers developed a case study reviewing threats against different sectors defined in the PPD.

Published
2021
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50. Case Study: Schistosomiasis of the Endocervical Canal, A Rarely Reported Localization

Author

Delavy, Martine, Heriniainasolo, Josea Lea, Catarino, Rosa, Viviano, Manuela, Petignat, Patrick, and Vassilakos, Pierre

Abstract

With a challenging diagnosis, schistosomiasis is a major public health issue worldwide, particularly in low-resource countries. The presence of Schistosoma ova in the female genital tract is a common finding, which may engender considerable suffering among women of child-bearing age. We report the asymptomatic case of endocervical schistosomiasis without visible exocervical lesions in a 41-yr-old Malagasy woman with human papillomavirus-positive status detected during a cervical cancer screening campaign in Andilampanahy, Madagascar. Schistosomiasis involving only the endocervical canal is rarely reported and can be diagnosed histologically with endocervical brushing, which therefore represents a minimally invasive and well-tolerated tool for disease detection.

Published
2020
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