[Delayed diagnosis of osteosarcoma in adults: a prognostic factor to be considered]. / Retraso en el diagnóstico de osteosarcoma en adultos: un factor pronóstico que debemos considerar.

INTRODUCTION: different variables have been associated with a worse prognosis of patients with osteosarcoma (OS), highlighting tumor size, location in the axial skeleton and the presence of metastases. The objective of this study is to analyze the prognostic impact of diagnostic delay in osteosarcoma in adults in the Mexican population in a center specialized in sarcomas. MATERIAL AND METHODS: retrospective cohort study from January 1, 2005, to December 31, 2016, 96 patients over 21 years of age with a diagnosis of osteosarcoma were analyzed. RESULTS: the median time to diagnosis from the onset of symptoms was six months (range: 2-36). This variable was dichotomized by applying the operator-dependent curve (ROC) analysis and we determined a cut-off value greater than five months, with an area under the curve (AUC) = 0.93 [95% CI 0.86-0.97], sensitivity 93.2% and specificity 94.6%. CONCLUSION: time until diagnosis is a critical factor in the survival of adult patients with osteosarcoma, highlighting its influence on disease progression and the appearance of metastasis. The correlation between diagnostic delay and an unfavorable prognosis reinforces the need for rapid and efficient evaluation in suspected cases of osteosarcoma.

INTRODUCCIÓN: diferentes variables se han asociado con un peor pronóstico de los pacientes con osteosarcoma, destacando el tamaño tumoral, la localización en esqueleto axial y la presencia de metástasis. El objetivo de este estudio fue analizar el impacto pronóstico del retraso diagnóstico en osteosarcoma en adultos en población mexicana en un centro especializado en sarcomas. MATERIAL Y MÉTODOS: estudio de tipo cohorte retrospectiva del 1 de Enero del 2005 al 31 de Diciembre de 2016, se analizaron 96 pacientes mayores de 21 años con diagnóstico de osteosarcoma. RESULTADOS: la mediana de tiempo al diagnóstico desde el inicio de síntomas fue de seis meses (rango: 2-36). Esta variable se dicotomizó aplicando el análisis de curva dependiente de operador (ROC) y determinamos un valor de corte mayor a cinco meses con un área bajo la curva (AUC) = 0.93 [IC95% 0.86-0.97], sensibilidad 93.2% y especificidad 94.6%. CONCLUSIÓN: el tiempo hasta el diagnóstico es un factor crítico en la supervivencia de los pacientes adultos con osteosarcoma, destacando su influencia en la progresión de la enfermedad y la aparición de metástasis. La correlación entre el retraso diagnóstico y un pronóstico desfavorable refuerza la necesidad de una evaluación rápida y eficiente en casos sospechosos de osteosarcoma.

Mitochondrial function in lungs of rats with different susceptibilities to hyperoxia-induced Acute Lung Injury.

Adult rats exposed to hyperoxia (>95% O2) die from respiratory failure in 60-72 hours. However, rats preconditioned with >95% O2 for 48 hours followed by 24 hours in room air (H-T) acquire tolerance of hyperoxia, while rats preconditioned with 60% O2 for 7 days (H-S) become more susceptible. Our objective was to evaluate lung tissue mitochondrial bioenergetics in H-T and H-S rats. Bioenergetics were assessed in mitochondria isolated from lung tissue of H-T, H-S, and control rats. Expressions of complexes involved in oxidative phosphorylation (OxPhos) were measured in lung tissue homogenate. Pulmonary endothelial filtration coefficient (Kf) and tissue mitochondrial membrane potential (ΔΨm) were evaluated in isolated perfused lungs. Results show that ADP-induced state 3 OxPhos capacity (Vmax) decreased in H-S mitochondria but increased in H-T. ΔΨm repolarization time following ADP-stimulated depolarization increased in H-S mitochondria. Complex I expression decreased in H-T (38%) and H-S (43%) lung homogenate, whereas complex V expression increased (70%) in H-T lung homogenate. ΔΨm is unchanged in H-S and H-T lungs, but complex II has a larger contribution to ΔΨm in H-S than H-T lungs. Kf increased in H-S, but not H-T lungs. For H-T, increased complex V expression and Vmax counter the effect of the decrease in complex I expression on ΔΨm. A larger complex II contribution to ΔΨm along with decreased Vmax and increased Kf could make H-S rats more hyperoxia susceptible. Results are clinically relevant since ventilation with ≥60% O2 is often required for extended periods in Acute Respiratory Distress Syndrome patients.

Assessing the degree of hepatic ischemia-reperfusion injury using PBPK modeling of sodium fluorescein disposition in ex vivo machine-perfused livers.

Ischemia-reperfusion injury (IRI) is an intrinsic risk associated with liver transplantation. Ex vivo hepatic machine perfusion (MP) is an emerging organ preservation technique that can mitigate IRI, especially in livers subjected to prolonged warm ischemia time (WIT). However, a method to quantify the biological response to WIT during MP has not been established. Previous studies used physiologically-based pharmacokinetic (PBPK) modeling to demonstrate that a decrease in hepatic transport and biliary excretion of the tracer molecule sodium fluorescein (SF) could correlate with increasing WIT in situ. Furthermore, these studies proposed intracellular sequestration of the hepatocyte canalicular membrane transporter multi-drug resistance-associated protein 2 (MRP2) leading to decreased MRP2 activity (maximal transport velocity; Vmax) as the potential mechanism for decreased biliary SF excretion. We adapted an extant PBPK model to account for ex vivo hepatic MP and fit a 6-parameter version of this model to control time course measurements of SF in MP perfusate and bile. We then identified parameters whose values were likely insensitive to changes in WIT and fixed them to generate a reduced model with only 3 unknown parameters. Finally, we fit the reduced model to each individual biological replicate SF time course with differing WIT and found the mean estimated value for each parameter and compared them using a one-way ANOVA. We demonstrated that there was a significant decrease in the estimated value of Vmax for MRP2 at 30 min WIT. These studies provide the foundation for future studies investigating real-time assessment of liver viability during ex vivo MP.

[Prognostic factors associated with failure of modular knee arthroplasty in oncologic patients]. / Factores pronósticos asociados al fracaso de la artroplastía modular de rodilla en pacientes oncológicos.

INTRODUCTION: reconstruction of large bone defects using modular knee arthroplasty (MKA) presents a significant challenge in terms of functionality. The objective of the present work was to identify the different prognostic factors associated with failure of MKA in cancer patients. MATERIAL AND METHODS: a retrospective cohort study was conducted, including patients with a diagnosis of musculoskeletal tumor in the distal femur or proximal tibia, who underwent MKA between January 1, 2010, and December 31, 2021. RESULTS: 49 patients were included, of which 25 (51.02%) were women and 24 (48.98%) men, with a mean age of 29.57 years. Of these, 14 (28.57%) patients experienced some type of MKA failure. The most frequent complication that led to failure was periprosthetic infection, observed in seven (14.29%) patients. Variables associated with MKA failure included biopsies performed outside our hospital (HR 3.2, 95% CI 1.4-6.4, p = 0.02), the length of the long axis of the tumor (HR 2.1, 95% CI 1.2-4.6, p = 0.01) and a prolonged surgical time (HR 3.37, 95% CI 1.1-8.6, p = 0.04). CONCLUSION: the most significant prognostic factors associated with MKA failure in our cohort were tumor size, prolonged surgical time, and performance of the diagnostic biopsy in a center not specialized in the management of this type of patient. These findings highlight the importance of considering these variables to improve outcomes in patients undergoing MKA.

INTRODUCCIÓN: la reconstrucción de grandes defectos óseos mediante artroplastía modular de rodilla (AMR) representa un desafío significativo en términos de funcionalidad. El objetivo del presente trabajo fue identificar los diferentes factores pronósticos asociados al fracaso de la AMR en pacientes oncológicos. MATERIAL Y MÉTODOS: se realizó un estudio de cohorte retrospectiva, incluyendo pacientes con diagnóstico de tumor musculoesquelético en el fémur distal o la tibia proximal, que fueron sometidos a AMR entre el 1 de Enero de 2010 y el 31 de Diciembre de 2021. RESULTADOS: se incluyeron 49 pacientes, de los cuales 25 (51.02%) eran mujeres y 24 (48.98%) hombres, con una edad media de 29.57 años. De éstos, 14 (28.57%) pacientes experimentaron algún tipo de fracaso de la AMR. La complicación más frecuente que condicionó el fracaso fue la infección periprotésica, observada en siete (14.29%) pacientes. Las variables asociadas con el fracaso de las AMR incluyeron biopsias realizadas fuera de nuestro hospital (HR 3.2, IC95% 1.4-6.4, p = 0.02), longitud del eje mayor del tumor (HR 2.1, IC95% 1.2-4.6, p = 0.01) y tiempo quirúrgico prolongado (HR 3.37, IC95% 1.1-8.6, p = 0.04). CONCLUSIÓN: los factores pronósticos asociados al fracaso de las AMR en nuestra cohorte fueron el tamaño del tumor, un tiempo quirúrgico prolongado y la realización de la biopsia diagnóstica en un centro no especializado en el manejo de este tipo de pacientes. Estos hallazgos resaltan la importancia de considerar estas variables en pacientes sometidos a AMR.

BioModME for building and simulating dynamic computational models of complex biological systems.

Summary: Molecular mechanisms of biological functions and disease processes are exceptionally complex, and our ability to interrogate and understand relationships is becoming increasingly dependent on the use of computational modeling. We have developed "BioModME," a standalone R-based web application package, providing an intuitive and comprehensive graphical user interface to help investigators build, solve, visualize, and analyze computational models of complex biological systems. Some important features of the application package include multi-region system modeling, custom reaction rate laws and equations, unit conversion, model parameter estimation utilizing experimental data, and import and export of model information in the Systems Biology Matkup Language format. The users can also export models to MATLAB, R, and Python languages and the equations to LaTeX and Mathematical Markup Language formats. Other important features include an online model development platform, multi-modality visualization tool, and efficient numerical solvers for differential-algebraic equations and optimization. Availability and implementation: All relevant software information including documentation and tutorials can be found at https://mcw.marquette.edu/biomedical-engineering/computational-systems-biology-lab/biomodme.php. Deployed software can be accessed at https://biomodme.ctsi.mcw.edu/. Source code is freely available for download at https://github.com/MCWComputationalBiologyLab/BioModME.

Highly efficient ceramic membrane synthesized from sugar scum and fly ash as sustainable precursors for dyes removal.

Recycling solid industrial wastes into valuable materials is always the priority solution in waste management. In this perspective, sugar scum and fly ash were used to produce an effective low-cost porous ceramic membrane. The impacts of the sintering temperature, amount of sugar scum, and sintering time on the properties of the prepared ceramic membrane were investigated and optimized using experimental design. A simultaneous rise in both the sintering temperature and the amount of sugar scum leads to a notable increase in porosity. Moreover, the simultaneous increase or decrease in the time and the amount of sugar scum causes a significant decrease in the compressive strength. The optimal conditions have been determined as a sintering temperature of 1197 °C, a sugar scum amount of 12.06 %, and a sintering time of 253 min. Under these conditions, the density, porosity, and compressive strength were found to be 2.16 g/cm³, 34.66 %, and 28.24 MPa, respectively. In addition, the obtained ceramic membrane has a water permeability of 2356.68 L/h m2 bar, a pore size in the range 0-4.5 µm, and excellent chemical resistance in both acidic and basic media. Finally, the performance of the prepared ceramic membrane was evaluated by the filtration of methylene blue. The results indicate that sugar scum and fly ash are suitable precursors to manufacture an effective ceramic membrane for the treatment of wastewater.

Physiologically-Based Pharmacokinetic Modeling of Blood Clearance of Liver Fluorescent Markers for the Assessment of the Degree of Hepatic Ischemia-Reperfusion Injury.

During liver transplantation, ischemia-reperfusion injury (IRI) is inevitable and decreases the overall success of the surgery. While guidelines exist, there is no reliable way to quantitatively assess the degree of IRI present in the liver. Our recent study has shown a correlation between the bile-to-plasma ratio of FDA-approved sodium fluorescein (SF) and the degree of hepatic IRI, presumably due to IRI-induced decrease in the activity of the hepatic multidrug resistance-associated protein 2 (MRP2); however, the contribution of SF blood clearance via the bile is still convoluted with other factors, such as renal clearance. In this work, we sought to computationally model SF blood clearance via the bile. First, we converted extant SF fluorescence data from rat whole blood, plasma, and bile to concentrations using calibration curves. Next, based on these SF concentration data, we generated a "liver-centric", physiologically-based pharmacokinetic (PBPK) model of SF liver uptake and clearance via the bile. Model simulations show that SF bile concentration is highly sensitive to change in the activity of hepatic MPR2. These simulations suggest that SF bile clearance along with the PBPK model can be used to quantify the effect of IRI on the activity of MRP2.Clinical Relevance- This study establishes the theory necessary to generate a model for predicting the degree of IRI during liver transplantation.

Risk factors and characteristics of hospitalized COVID-19 patients in Jordan.

OBJECTIVES: To investigate the occurrence and identify the factors contributing to hospitalization among individuals diagnosed with COVID-19. METHODS: From June 15, 2020 to September 30, 2020, a cross-sectional study utilizing an online questionnaire was carried out in Jordan. The study included 657 COVID-19 patients who had recovered and had reached a minimum of 3 months post-illness. Sociodemographic and COVID-19-related data were collected. The questionnaire was distributed to members of the "My Experience with COVID-19 Association" in Jordan. RESULTS: The prevalence of hospitalization among COVID-19 patients was 3%. Patients with hypertension (p=0.00), diabetes mellitus (p=0.00), and heart disease (p=0.009); using angiotensin-converting enzyme inhibitors (ACE) and angiotensin-receptor blockers (ARBs) (p=0.00); with body mass indexes (BMI) above normal (p=0.005); and aged over 45 years (p=0.00) were at higher risk of hospitalization. Using an odds ratio (OR), hypertension (OR=7.1), diabetes mellitus (OR=11.4), heart disease (OR=6.3), angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers use (OR=10.8), and having a BMI >25 (OR=5) were significant hospitalization risk factors. The seasonal influenza vaccine, smoking, and neuropsychological symptoms showed no significance. CONCLUSION: Identifying high-risk groups can help them monitor their health and take preventive measures against COVID-19 infection.

Computational Modeling of Substrate-Dependent Mitochondrial Respiration and Bioenergetics in the Heart and Kidney Cortex and Outer Medulla.

Integrated computational modeling provides a mechanistic and quantitative framework to characterize alterations in mitochondrial respiration and bioenergetics in response to different metabolic substrates in-silico. These alterations play critical roles in the pathogenesis of diseases affecting metabolically active organs such as heart and kidney. Therefore, the present study aimed to develop and validate thermodynamically constrained integrated computational models of mitochondrial respiration and bioenergetics in the heart and kidney cortex and outer medulla (OM). The models incorporated the kinetics of major biochemical reactions and transport processes as well as regulatory mechanisms in the mitochondria of these tissues. Intrinsic model parameters such as Michaelis-Menten constants were fixed at previously estimated values, while extrinsic model parameters such as maximal reaction and transport velocities were estimated separately for each tissue. This was achieved by fitting the model solutions to our recently published respirometry data measured in isolated rat heart and kidney cortex and OM mitochondria utilizing various NADH- and FADH2-linked metabolic substrates. The models were validated by predicting additional respirometry and bioenergetics data, which were not used for estimating the extrinsic model parameters. The models were able to predict tissue-specific and substrate-dependent mitochondrial emergent metabolic system properties such as redox states, enzyme and transporter fluxes, metabolite concentrations, membrane potential, and respiratory control index under diverse physiological and pathological conditions. The models were also able to quantitatively characterize differential regulations of NADH- and FADH2-linked metabolic pathways, which contribute differently toward regulations of oxidative phosphorylation and ATP synthesis in the heart and kidney cortex and OM mitochondria.

Aortic Remodeling Kinetics in Response to Coarctation-Induced Mechanical Perturbations.

Background: Coarctation of the aorta (CoA; constriction of the proximal descending thoracic aorta) is among the most common congenital cardiovascular defects. Coarctation-induced mechanical perturbations trigger a cycle of mechano-transduction events leading to irreversible precursors of hypertension including arterial thickening, stiffening, and vasoactive dysfunction in proximal conduit arteries. This study sought to identify kinetics of the stress-mediated compensatory response leading to these alterations using a preclinical rabbit model of CoA. Methods: A prior growth and remodeling (G&R) framework was reformulated and fit to empirical measurements from CoA rabbits classified into one control and nine CoA groups of various severities and durations (n = 63, 5-11/group). Empirical measurements included Doppler ultrasound imaging, uniaxial extension testing, catheter-based blood pressure, and wire myography, yielding the time evolution of arterial thickening, stiffening, and vasoactive dysfunction required to fit G&R constitutive parameters. Results: Excellent agreement was observed between model predictions and observed patterns of arterial thickening, stiffening, and dysfunction among all CoA groups. For example, predicted vascular impairment was not significantly different from empirical observations via wire myography (p-value > 0.13). Specifically, 48% and 45% impairment was observed in smooth muscle contraction and endothelial-dependent relaxation, respectively, which were accurately predicted using the G&R model. Conclusions: The resulting G&R model, for the first time, allows for prediction of hypertension precursors at neonatal ages that is currently challenging to examine in preclinical models. These findings provide a validated computational tool for prediction of persistent arterial dysfunction and identification of revised severity-duration thresholds that may ultimately avoid hypertension from CoA.

Effects of ROS pathway inhibitors and NADH and FADH2 linked substrates on mitochondrial bioenergetics and ROS emission in the heart and kidney cortex and outer medulla.

Mitochondria are major sources of reactive oxygen species (ROS), which play important roles in both physiological and pathological processes. However, the specific contributions of different ROS production and scavenging components in the mitochondria of metabolically active tissues such as heart and kidney cortex and outer medulla (OM) are not well understood. Therefore, the goal of this study was to determine contributions of different ROS production and scavenging components and provide detailed comparisons of mitochondrial respiration, bioenergetics, ROS emission between the heart and kidney cortex and OM using tissues obtained from the same Sprague-Dawley rat under identical conditions and perturbations. Specifically, data were obtained using both NADH-linked substrate pyruvate + malate and FADH2-linked substrate succinate followed by additions of inhibitors of different components of the electron transport chain (ETC) and oxidative phosphorylation (OxPhos) and other ROS production and scavenging systems. Currently, there is limited data available for the mitochondria of kidney cortex and OM, the two major energy-consuming tissues in the body only next to the heart, and scarce quantitative information on the interplay between mitochondrial ROS production and scavenging systems in the three tissues. The findings from this study demonstrate significant differences in mitochondrial respiratory and bioenergetic functions and ROS emission among the three tissues. The results quantify the rates of ROS production from different complexes of the ETC, identify the complexes responsible for variations in mitochondrial membrane depolarization and regulations of ROS production, and quantify the contributions of ROS scavenging enzymes towards overall mitochondrial ROS emission. These findings advance our fundamental knowledge of tissue-specific and substrate-dependent mitochondrial respiratory and bioenergetic functions and ROS emission. This is important given the critical role that excess ROS production, oxidative stress, and mitochondrial dysfunction in the heart and kidney cortex and OM play in the pathogenesis of cardiovascular and renal diseases, including salt-sensitive hypertension.

Manufacturing methods, properties, and potential applications in bone tissue regeneration of hydroxyapatite-chitosan biocomposites: A review.

Hydroxyapatite (HA) and chitosan (CS) biopolymer are the major materials investigated for biomedical purposes. Both of these components play an important role in the orthopedic field as bone substitutes or drug release systems. Used separately, the hydroxyapatite is quite fragile, while CS mechanical strength is very weak. Therefore, a combination of HA and CS polymer is used, which provides excellent mechanical performance with high biocompatibility and biomimetic capacity. Moreover, the porous structure and reactivity of the hydroxyapatite-chitosan (HA-CS) composite allow their application not only as a bone repair but also as a drug delivery system providing controlled drug release directly to the bone site. These features make biomimetic HA-CS composite a subject of interest for many researchers. Through this review, we provide the important recent achievements in the development of HA-CS composites, focusing on manufacturing techniques, conventional and novel three-dimensional bioprinting technology, and physicochemical and biological properties. The drug delivery properties and the most relevant biomedical applications of the HA-CS composite scaffolds are also presented. Finally, alternative approaches are proposed to develop HA composites with the aim to improve their physicochemical, mechanical, and biological properties.

An overview of underutilized benefits derived from Azolla as a promising biofertilizer in lowland rice production.

Currently, there is no doubt that Azolla can compensate for the nitrogen requirements of rice in different agroecological zones. Compared to synthetic N-fertilizers, Azolla has various positive impacts on lowland rice production, including improving soil fertility, minimizing weeds, increasing soil organic carbon, improving microbial biomass, and thus nutrient cycling and enhancing rice growth and yield. However, Azolla has not been accepted globally by rice farmers for field use and so far, farmers are relying on increasing rates of synthetic N fertilizers instead of taking advantage of Azolla which will improve long-term soil fertility and health. This systematic literature review and scientific evidence could help policymakers, scientists and researchers to understand the benefits, limitations, and innovative ways of utilizing Azolla as a cost-effective and eco-friendly amendment in rice production. The paper uses Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) method to review the hidden potential of Azolla as a biofertilizer in paddy and summarizes its benefits and problems by collecting information from different sources and presenting under different subheadings such as critical factors affecting Azolla growth and nitrogen fixation, nitrogen fixation of Anabaena Azollae and their contribution in soil health, release and availability of Azolla-N to rice, amounts and time of Azolla inoculation, influence of Azolla on ammonia volatilization, contribution of Azolla to yield and yield components of rice, and impact of Azolla on weed emergence in rice cropping system. Literature indicated that the use of Azolla as green manure incorporated before rice transplanting or grown together with rice and left until a few days of harvest alone or in combinations with other synthetic fertilizers in the lowland rice production saved the nitrogen requirement of rice up to 60 kg N ha-1, it enhances the availability of nutrients, improves physiochemical properties of soils, minimizes soil salinity, reduces the soil pH, and minimize weed germination. However, it was observed that incorporating Azolla as green manure is labor-intensive, and maintaining the Azolla inocula and phosphorous requirement are major restrictions for farmers. Therefore, understanding mechanism of spore production, educating farmers on cheaper alternative ways of Azolla application, and testing different species of Azolla over different agroecological zones will help in maintaining Azolla biomass and applying it at low cost for further environmental conservation.

Ab initio investigations of a CoBiS monolayer with and without point defects.

Through density functional theory (DFT) calculations, a new triclinic monolayer, namely CoBiS, with higher stability than that of penta-CoBiS, is predicted. Our results show that this monolayer is a nonmagnetic metallic compound. To tune its magnetic properties, we systematically investigated the formation and energetics of different point defects in the CoBiS monolayer, such as VBi, VS and VCo. We find that the monolayer becomes magnetic with the different points defects. Our calculated magnetic anisotropy energy (MAE) indicated that VBi and VS exhibit out-of-plane MAE, while the MAE is in-plane for VCo. By solving the Heisenberg model using the Monte Carlo simulation method, we obtain transition temperatures for VS and VCo systems much larger than room temperature, implying potential applications in spintronic devices.

Sustainable phosphorylated microcrystalline cellulose toward enhanced removal performance of methylene blue.

In this study, microcrystalline cellulose (MCC) was phosphorylated using phosphoric acid in the presence of urea and used as an adsorbent for methylene blue (MB) dye removal from an aqueous solution. The obtained products were characterized by different techniques. Batch adsorption experiments were conducted under varying conditions of incubation time, initial MB concentration, pH, and phosphorylation degree. All the samples exhibited similar and fast adsorption kinetics, described by pseudo-second-order model for MB adsorption, whereas the retention capacity depended significantly on the phosphate content and the surface charge of the adsorbents. The experimental adsorption data in the examined MB initial concentrations (0-2000 mg/L) were best suited by the Langmuir isotherm model. The study revealed that the presence of phosphates groups in the cellulose structure significantly enhanced the adsorption of the MB pollutant. The maximum dye removal capacity at pH of 7 was obtained for the phosphorylated microcrystalline cellulose (284.03 mg/g) with a high phosphorylation degree (1.92 % of P), which is 20 times higher than unmodified MCC (15.29 mg/g). This property increased from 284.03 to 328.32 mg/g when increasing the pH from 7 to 11. The MB adsorption mechanism involves hydrogen bonding, electrostatic and ion-dipole interactions. These findings are relevant to a better understanding of the role of cellulose phosphorylation in the recovery of organic dyes from the waste liquid of many industries.

[Surgical margins as prognostic factor in pelvis chondrosarcoma. Cohort study in a sarcoma unit]. / Márgenes quirúrgicos como factor pronóstico del condrosarcoma de pelvis. Estudio de cohorte en una unidad de sarcomas.

INTRODUCTION: chondrosarcoma is the second most common primary malignant tumor, constitutes approximately one quarter of all primary bone sarcomas. Surgical margins in pelvic chondrosarcoma have a direct impact as a prognostic factor, both on overall survival and on recurrence-free survival of this disease. OBJECTIVES: to analyze the impact of surgical margins as a prognostic factor in pelvic chondrosarcoma. MATERIAL AND METHODS: a retrospective database cohort with prospective follow-up of sarcomas in patients diagnosed with primary pelvic chondrosarcoma who underwent surgical treatment. Clinical-demographic variables were obtained, a descriptive analysis of each variable was performed, and these were contrasted with the outcome variables. RESULTS: seventeen patients were included, of which nine were female. The median age was 41 years, ranging from 23 to 65 years. The average tumor size was 20.9 cm (range 5 to 46 cm). The average surgical margin was 5.3 mm, ranging from 1 to 30 mm, with 58% positive margins. The average overall survival was 64 months (range 7 to 108 months). The distribution of pelvic involvement was as follows: zone I in nine patients (52.9%), zone II in two (11.8%), a combination of zones I-III in two (11.8%), I+II in one (5.9%), II+III in one (5.9%), I-III plus sacrum in one (5.9%) and I plus sacrum in one (5.9%). Tumor grades were classified as low in seven patients (41.2%), intermediate in sven (41.2%), high in two (11.8%), and dedifferentiated in one (5.9%). Regarding the type of resection, 12 patients (70.6%) underwent internal hemipelvectomy and five (29.4%) external hemipelvectomy. Recurrence was recorded in five cases (29.4%), metastasis in three (17.6%), and mortality in four (23.5%). CONCLUSIONS: this series represents the largest cohort reported in Latin America of primary pelvic chondrosarcomas. A more favorable prognosis was observed in patients with surgical margins greater than 1 mm. The presence of chondrosarcoma in multiple pelvic zones was associated with a worse oncological prognosis. Additionally, a higher incidence of positive surgical margins and local recurrence rates were identified in pelvic chondrosarcomas compared to those located in the extremities.

INTRODUCCIÓN: el condrosarcoma (CS), el segundo tumor maligno óseo primario más común, constituye aproximadamente una cuarta parte de todos los sarcomas óseos primarios. Los márgenes quirúrgicos en el condrosarcoma pélvico tienen un impacto directo como factor pronóstico, tanto en la supervivencia global como en la supervivencia libre de recurrencia de esta enfermedad. OBJETIVOS: analizar el impacto de los márgenes quirúrgicos como factor pronóstico en el condrosarcoma de la pelvis. MATERIAL Y MÉTODOS: cohorte de base de datos retrospectiva con seguimiento prospectivo de sarcomas de pacientes con diagnóstico de condrosarcoma primario de la pelvis que fueron sometidos a tratamiento quirúrgico. Se obtuvieron variables clínico-demográficas, se realizó un análisis descriptivo de cada variable y se contrastaron con las variables desenlace. RESULTADOS: se incluyeron 17 pacientes, de los cuales nueve eran mujeres. La mediana de edad fue de 41 años (rango de 23 a 65 años). El tamaño promedio del tumor fue de 20.9 cm (rango de 5 a 46 cm). El margen quirúrgico promedio fue de 5.3 mm, variando entre 1 y 30 mm, con 58% de márgenes positivos. La supervivencia global promedio fue de 64 meses (rango de 7 a 108 meses). La distribución de la afectación pélvica fue: zona I en nueve pacientes (52.9%), zona II en dos (11.8%), combinación de zonas I-III en dos (11.8%), I+II en uno (5.9%), II+III en uno (5.9%), I-III más sacro en uno (5.9%) y I más sacro en uno (5.9%). Los grados tumorales se clasificaron en bajo en siete pacientes (41.2%), intermedio en siete (41.2%), alto en dos (11.8%) y desdiferenciado en uno (5.9%). Respecto al tipo de resección, 12 pacientes (70.6%) se sometieron a hemipelvectomía interna y cinco (29.4%) a hemipelvectomía externa. Se registró recurrencia en cinco casos (29.4%), metástasis en tres (17.6%) y mortalidad en cuatro (23.5%). CONCLUSIONES: esta serie representa la cohorte más extensa reportada en Latinoamérica de condrosarcomas primarios de la pelvis. Se observó un pronóstico más favorable en pacientes con márgenes quirúrgicos superiores a 1 mm. La presencia de condrosarcoma en múltiples zonas pélvicas se asoció con un peor pronóstico oncológico. Además, se identificó una mayor incidencia de márgenes quirúrgicos positivos y tasas de recurrencia local en condrosarcomas de la pelvis en comparación con aquellos ubicados en las extremidades.

Impact of COVID-19 on Student's Dental Education and Life.

Objectives: We sought to identify the impact of the COVID-19 pandemic on the Oman Dental College (ODC) students' management of their educational and student life. Methods: We conducted a quantitative cross-sectional online survey study using SurveyMonkey. During the 2019-2020 academic year, 383 ODC students across six levels of education were invited to participate in the survey. Descriptive statistics were applied to the students' demographic profiles, and other characteristics of the participants' data were analyzed. Cronbach's alpha was calculated for internal consistency. A univariate analysis was carried out to identify the differences between genders and between the Bachelor of Dental Surgery levels in relation to the questionnaire themes. A Pearson's correlation test evaluated the association between students' perception of risks due to the pandemic and the other relevant themes. Results: A 50.9% response rate revealed that five of the themes showed internal reliability ranging from excellent to acceptable, namely: performance of exercise, effect of the pandemic on their families, use of a facemask, college's online services, and students' mental health (0.51, 0.59, 0.70, 0.78, and 0.90, respectively). More than half of the participants felt encouraged to engage in self-directed learning using online resources. They felt some level of nervousness, worry, anxiety, or tension as well as stress during the pandemic. Statistical differences between levels of education were noted in the ODC's-online teaching services (p < 0.001) and students' mental health (p = 0.03). There was no difference between female and male students. The ODC's online services theme positively related to the students' mental health theme (r = 0.22, p < 0.001). Conclusions: ODC students experienced some mental health issues during the pandemic, including anxiety, stress, and sleeping issues. However, the majority of them were healthy. Most students were satisfied with the online teaching provided by ODC. It was also evident that faculty were always connected with the students. A positive relationship was noted between the management of online lectures and students' mental health.