Predicting major adverse cardiovascular events after orthotopic liver transplantation using a supervised machine learning model: A cohort study.

BACKGROUND: Liver transplant (LT) patients have become older and sicker. The rate of post-LT major adverse cardiovascular events (MACE) has increased, and this in turn raises 30-d post-LT mortality. Noninvasive cardiac stress testing loses accuracy when applied to pre-LT cirrhotic patients. AIM: To assess the feasibility and accuracy of a machine learning model used to predict post-LT MACE in a regional cohort. METHODS: This retrospective cohort study involved 575 LT patients from a Southern Brazilian academic center. We developed a predictive model for post-LT MACE (defined as a composite outcome of stroke, new-onset heart failure, severe arrhythmia, and myocardial infarction) using the extreme gradient boosting (XGBoost) machine learning model. We addressed missing data (below 20%) for relevant variables using the k-nearest neighbor imputation method, calculating the mean from the ten nearest neighbors for each case. The modeling dataset included 83 features, encompassing patient and laboratory data, cirrhosis complications, and pre-LT cardiac assessments. Model performance was assessed using the area under the receiver operating characteristic curve (AUROC). We also employed Shapley additive explanations (SHAP) to interpret feature impacts. The dataset was split into training (75%) and testing (25%) sets. Calibration was evaluated using the Brier score. We followed Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines for reporting. Scikit-learn and SHAP in Python 3 were used for all analyses. The supplementary material includes code for model development and a user-friendly online MACE prediction calculator. RESULTS: Of the 537 included patients, 23 (4.46%) developed in-hospital MACE, with a mean age at transplantation of 52.9 years. The majority, 66.1%, were male. The XGBoost model achieved an impressive AUROC of 0.89 during the training stage. This model exhibited accuracy, precision, recall, and F1-score values of 0.84, 0.85, 0.80, and 0.79, respectively. Calibration, as assessed by the Brier score, indicated excellent model calibration with a score of 0.07. Furthermore, SHAP values highlighted the significance of certain variables in predicting postoperative MACE, with negative noninvasive cardiac stress testing, use of nonselective beta-blockers, direct bilirubin levels, blood type O, and dynamic alterations on myocardial perfusion scintigraphy being the most influential factors at the cohort-wide level. These results highlight the predictive capability of our XGBoost model in assessing the risk of post-LT MACE, making it a valuable tool for clinical practice. CONCLUSION: Our study successfully assessed the feasibility and accuracy of the XGBoost machine learning model in predicting post-LT MACE, using both cardiovascular and hepatic variables. The model demonstrated impressive performance, aligning with literature findings, and exhibited excellent calibration. Notably, our cautious approach to prevent overfitting and data leakage suggests the stability of results when applied to prospective data, reinforcing the model's value as a reliable tool for predicting post-LT MACE in clinical practice.

Can hard and/or soft occlusal splints reduce the bite force transmitted to the teeth and temporomandibular joint discs? A finite element method analysis.

OBJECTIVE: To test whether two different materials used for occlusal splints would reduce the stress to the temporomandibular joint discs. METHODS: Geometric data from a young-adult male patient were obtained from computed tomography and magnetic resonance imaging. 3D biomodels and the finite element analyses were performed using specific software. RESULTS: The mandibular model presented the highest bone stress areas in the mandibular rami and insertion of the temporalis muscles. Regardless the material, the highest stress in the occlusal splints was located in the second molar regions on the occlusal splint surface and in the opposing mandibular second molars. Stress reduction was only observed in the internal surface of the occlusal splints embracing the maxillary teeth. No differences between occlusal splints were found in the stress intensity and distribution in either left or right TMJ discs, being concentrated more in the anterior portion of the disc. DISCUSSION: Hard acrylic OS should be preferred over soft EVA OS in the majority of cases, soft OS only for temporary use. Thinner OS (2-3 mm anterior thickness) should be preferred over thick ones (3-4 mm) in order to keep the stress concentrations in the center of the TMJ discs. Lighter contacts over heavier contacts should be preferred in the second molar OS contact surface area to prevent stress concentrations and fractures. Maxillary occlusal splints should be chosen if the teeth or implant are in the maxilla, and vice-versa.

Use of artificial intelligence to predict response to neoadjuvant chemotherapy in breast cancer

:Breast cancer is the object of thousands of studies worldwide. Nevertheless, few tools are available to corroborate prediction of response to neoadjuvant chemotherapy. Artificial intelligence is being researched for its potential utility in several fields of knowledge, including oncology. The development of a standardized Artificial intelligence-based predictive model for patients with breast cancer may help make clinical management more personalized and effective. We aimed to apply Artificial intelligence models to predict the response to neoadjuvant chemotherapy based solely on clinical and pathological data. Methods: Medical records of 130 patients treated with neoadjuvant chemotherapy were reviewed and divided into two groups: 90 samples to train the network and 40 samples to perform prospective testingand validate the results obtained by the Artificial intelligence method. Results: Using clinicopathologic data alone, the artificial neural network was able to correctly predict pathologic complete response in 83.3% of the cases. It also correctly predicted 95.6% of locoregional recurrence, as well as correctly determined whether patients were alive or dead at a given time point in 90% of the time. To date, no published research has used clinicopathologic data to predict the response to neoadjuvant chemotherapy in patients with breast cancer, thus highlighting the importance of the present study. Conclusions: Artificial neural network may become an interesting tool for predicting response to neoadjuvant chemotherapy, locoregional recurrence, systemic disease progression, and survival in patients with breast cancer (AU)

Perception of gender discrimination among spine surgeons across Latin America: a web-based survey.

BACKGROUND CONTEXT: Female physicians rarely choose spine surgery as their specialty. Although the specialty's nature and its associated lifestyle are potential barriers, gender-related issues may play an important part. PURPOSE: To evaluate the gender discrimination among spine surgeons across Latin America. STUDY DESIGN: Cross-sectional survey. PATIENT SAMPLE: The participants in this study were 223 AO Spine Latin America (AOSLA) registered members who answered the web-based survey. OUTCOME MEASURES: Personal and professional demographics; gender-related objective and subjective experiences regarding career and personal life. METHODS: A survey link containing a 24-item questionnaire was sent to the members' e-mails in September 2019. The survey was designed to evaluate the perception of gender discrimination by spine surgeons during their academic and professional lives. RESULTS: Out of 223 members who answered the survey, 196 (87.96%) were male and 27 (12.11%) female. Most were orthopedic surgeons (64.13%), ≥40 years of age (55.16%), and had <20 years of experience (69.95%). Gender discrimination was more frequent among women than among men (66.67% vs. 1.02%), as did discouragement from becoming a spine surgeon, orthopedic surgeon, or neurosurgeon (81.48% vs. 0.51%). Females reported higher rates of sexual harassment (44.44% vs. 7.65%) and more often felt disadvantaged because of gender (55.56% vs. 2.55%). Working harder than men to achieve the same prestige and lack of female mentorship were the most common obstacles reported by women (55.56%). Residency/fellowship influenced the decision to postpone/avoid having children for 66.67% of women but only 37.75% of men. Creation of a Women's Committee in AO Spine was supported by 74.07% of women and 38.78% of men. CONCLUSIONS: Gender-based discrimination affects women more frequently than men in spine surgery. These experiences likely contribute to the low prevalence of female spine surgeons. Efforts to mitigate bias and support the professional development of women in neurosurgery, orthopedics and spine communities are encouraged.

Reliability-Based Design Optimization of a Cemented Prosthesis in a Femur Undergoing Bone Remodeling.

This study proposes a numerical methodology to minimize the bone mass loss in a femur with a total hip arthroplasty procedure, considering uncertainties in the material parameters and using a reliability-based design optimization (RBDO) procedure. A genetic algorithm (GA) is applied for optimization, and a three-dimensional finite element (FE) model associated with the bone remodeling procedure is proposed and described to account for the internal and external femoral bone behavior. An example of a femoral prosthesis design is presented as a basis for discussion of the proposed methodologies, and the corresponding reliability level is evaluated. Constraints on the strength of all materials and target reliability levels are inputs to the optimization model. The main prosthesis dimensions and Young modulus are the design variables. The proposed methodology is compared with a well-known deterministic optimization (DO) procedure and the results show that it is important to consider the uncertainties in this kind of problem since in this case, the a posteriori reliability may be low.

Catheter-related infection due to Papiliotrema laurentii in an oncologic patient: Case report and systematic review

ABSTRACT Background: Papiliotrema laurentii is one of several non-neoformans cryptococci that have rarely been associated with human infection, since it was previously considered saprophyte and thought to be non-pathogenic to humans. Nevertheless, increasing number of reports of human infection have emerged in recent years, mostly in oncologic patients. Aim: To report a case of a female patient with pyloric obstructive cancer with a catheter-related Papiliotrema laurentii blood stream infection and systematically review the available evidence on P. laurentii infection in humans. Methods: Retrieval of studies was based on Medical Subject Headings and Health Sciences Descriptors, which were combined using Boolean operators. Searches were run on the electronic databases Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), Cochrane Library for Systematic Reviews and Opengray.eu. There was no language or date of publication restrictions. The reference lists of the studies retrieved were searched manually. Results: The search strategy retrieved 1703 references. In the final analysis, 31 references were included, with the description of 35 cases. Every patient but one had a previous co-morbidity - 48.4 % of patients had a neoplasm. Amphotericin B was the most used treatment and only a single case of resistance to it was reported. Most patients were cured of the infection. Conclusion: P. laurentii infection in humans is usually associated to neoplasia and multiple co-morbidities, and amphotericin B seems to be a reliable agent for treatment.

Catheter-related infection due to Papiliotrema laurentii in an oncologic patient: Case report and systematic review.

BACKGROUND: Papiliotrema laurentii is one of several non-neoformans cryptococci that have rarely been associated with human infection, since it was previously considered saprophyte and thought to be non-pathogenic to humans. Nevertheless, increasing number of reports of human infection have emerged in recent years, mostly in oncologic patients. AIM: To report a case of a female patient with pyloric obstructive cancer with a catheter-related Papiliotrema laurentii blood stream infection and systematically review the available evidence on P. laurentii infection in humans. METHODS: Retrieval of studies was based on Medical Subject Headings and Health Sciences Descriptors, which were combined using Boolean operators. Searches were run on the electronic databases Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), Cochrane Library for Systematic Reviews and Opengray.eu. There was no language or date of publication restrictions. The reference lists of the studies retrieved were searched manually. RESULTS: The search strategy retrieved 1703 references. In the final analysis, 31 references were included, with the description of 35 cases. Every patient but one had a previous co-morbidity - 48.4 % of patients had a neoplasm. Amphotericin B was the most used treatment and only a single case of resistance to it was reported. Most patients were cured of the infection. CONCLUSION: P. laurentii infection in humans is usually associated to neoplasia and multiple co-morbidities, and amphotericin B seems to be a reliable agent for treatment.

Stress Distribution Study Using the Finite Element Method in Three Different Implant-Supported Fixed Complete-Arch Mandibular Prostheses.

PURPOSE: The objective of this study was to assess the stress distribution generated by a simulated loading (100 N) in the area of the cantilever in three different five-implant mandibular protocol prosthesis models. MATERIALS AND METHODS: The finite element analysis was carried out in three-dimensional models simulating: (1) a temporary all acrylic resin mandibular protocol prosthesis; (2) a metal-acrylic mandibular protocol prosthesis; and (3) a metal-ceramic mandibular protocol prosthesis. RESULTS: The all acrylic model promoted the highest stress values on the implant closest to the cantilever loading point. CONCLUSION: This study supports the need for a metallic bar reinforcement in the denture base.

Optimization of a Cemented Femoral Prosthesis Considering Bone Remodeling.

The study presents a numerical methodology for minimizing the bone loss in human femur submitted to total hip replacement (THR) procedure with focus on cemented femoral stem. Three-dimensional computational models were used to describe the femoral bone behavior. An optimization procedure using the genetic algorithm (GA) method was applied in order to minimize the bone loss, considering the geometry and the material of the prosthesis as well as the design of the stem. Internal and external bone remodeling were analyzed numerically. The numerical method proposed here showed that the bone mass loss could be reduced by 24%, changing the design parameters.

Femoral stem-bone interface analysis of logical uncemented stem / Análise numérica do comportamento biomecânico da haste femoral não-cimentada Logical

This paper evaluates the mechanical behavior of an uncemented hip stem using finite element analysis. The analysis is focused on the stem-bone interaction which is assessed by simulation of distinct conditions encountered daily on orthopedic practice of hip implants. Logical uncemented femoral stem was used in this work. Three distinct conditions have been modeled: a) exposed neck with fully embedded fins, b) partially exposed anti-rotational fins and c) fully exposed fins, representing real femoral hip conditions. Anthropometric variations and different angulations for the stem neck were investigated for typical body weight of populations submitted to implants. The ratio of mobilized stress to yield stress is shown to be lower than 55% indicating a safety factor against stem failure. Although small displacements are observed in all conditions, the displacement increases with the increase of both the length of exposed fins and the magnitude of applied forces. Even for the extreme condition of fully exposed fins, the prostheses will support the working loads, and the risk of bone fracture still has a safety factor. Stresses and displacements change considerably with neck angulations suggesting that anthropometric variations should be considered in the future to optimize prostheses performance. Numerical analysis of the used uncemented femoral stem demonstrated that small stresses and strains are generated under working load conditions indicating that a proper factor of safety is obtained for the static conditions tested in the present study.

A presente pesquisa avalia o comportamento mecânico da haste femoral não-cimentada Logical através de elementos finitos. Foram analisadas diferentes condições de contorno encontradas na prática ortopédica: a) apenas o colo exposto; b) com as aletas anti-rotatórias parcialmente expostas; e c) com as aletas totalmente expostas. Variações antropométricas foram consideradas pelas diferentes angulações de colo propostas e através de diferentes cargas aplicadas. A haste apresentou um bom coeficiente de segurança. Embora pequenos deslocamentos sejam observados em todas as condições, existe um maior deslocamento com o aumento da exposição das aletas da prótese. Mesmo para a condição extrema com as aletas totalmente expostas, a prótese suporta as cargas de trabalho e ainda há um bom fator de segurança. Tensões e deslocamentos se modificam consideravelmente com as diferentes angulações propostas para o colo, sugerindo que as variações antropométricas devam ser consideradas no futuro para otimizar o desempenho da prótese.

Estresse ao osso em torno de implantes ortodônticos na região de molares inferiores: uma avaliação por elementos finitos / Stress to the bone around orthodontic implants in the mandibular molar region: a finite element evaluation

Mini-screw implants have been commonly used for orthodontic anchorage. However, the behavior of implants may vary according to their location, inclination, loading position and loading direction. The objective of this study was to apply finite element to analyze stress distribution around mini-implants inserted into the buccal cortical bone, in the inferior molar region, when a force of 3 N was applied, varying implant inclination and loading direction, also simulating immediate loading and osseointegration conditions. We carried out a threedimensional analysis of a human cadaveric mandible and of a 9 mm length, 1.5 mm diameter titanium implant. The implant model was introduced into the buccal cortical bone, between the first and second mandibular molars. Finite-element analysis of the implant-bone structure was carried out applying a constant force of 3 N at varying angles (15, 30, 45, 60, 75, and 90 degrees), and in five different positions along the bone surface axis (perpendicularly, vertically at ± 10 degrees, and horizontally at ± 20 degrees). Out of all combinations tested, stress affected only the cortical bone, not being intense enough to cause cortical bone resorption. Stress distribution varied slightly (8.55 to 38.74 Mpa) due to implant inclination and loading direction. Immediate loading generated greater tensions (12.70 to 38.74 Mpa) when compared to osseointegration (8.55 to 21.44 Mpa). A force of 3 N did not result in a tension that could cause cortical bone resorption. Immediate loading resulted in greater tensions to the bone, regardless of implant inclination and loading direction.

Mini-implantes têm sido utilizados para ancoragem ortodôntica e seu comportamento pode variar de acordo com a sua localização e inclinação, com a posição e a direção da carga aplicada. Este estudo analisou a distribuição de tensões ao osso em torno de mini-implantes inseridos no osso cortical na região de molares inferiores, quando uma carga de 3 N é aplicada, variando a inclinação do implante e a direção da força,assim como situações de carga imediata e osseointegração. Uma mandíbula humana e um implante de titânio com 9 mm de comprimento e 1,5mm de diâmetro foram modelados, com o implante introduzido na face vestibular entre o primeiro e o segundo molares. Este modelo foi analisado pelo método de elementos finitos aplicando força constante de 3N com angulagens de 15, 30, 45, 60 e 75 graus, com o implante perpendicular ao osso e com inclinação vertical de 10 graus e horizontal de 20 graus. Em todas as combinações testadas a tensão afetou apenas o osso cortical, porém não apresentou intensidade suficiente para resultar em reabsorção óssea. Sua distribuição variou (8,55 a 38,74 Mpa) em função da inclinação do implante e da direção da carga. A situação de carga imediata gerou maiores tensões (12,70 a 38.74 Mpa) quando comparada à osseointegração (8,55 a 21,44 Mpa). Conclui-se que uma força de 3N não resulta em tensão que possa causar reabsorção da cortical óssea e que a carga imediata produz maior tensão ao osso, independentemente da inclinação do implante e da direção da força.