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Non-Newtonian transport properties of a dilute gas of inelastic hard spheres immersed in a molecular gas are determined. We assume that the granular gas is sufficiently rarefied, and hence the state of the molecular gas is not disturbed by the presence of the solid particles. In this situation, one can treat the molecular gas as a bath (or thermostat) of elastic hard spheres at a given temperature. Moreover, in spite of the fact that the number density of grains is quite small, we take into account their inelastic collisions among themselves in its kinetic equation. The system (granular gas plus a bath of elastic hard spheres) is subjected to a simple (or uniform) shear flow. In the low-density regime, the rheological properties of the granular gas are determined by solving the Boltzmann kinetic equation by means of Grad's moment method. These properties turn out to be highly nonlinear functions of the shear rate and the remaining parameters of the system. Our results show that the kinetic granular temperature and the non-Newtonian viscosity present a discontinuous shear thickening effect for sufficiently high values of the mass ratio m/m_{g} (m and m_{g} being the mass of grains and gas particles, respectively). This effect becomes more pronounced as the mass ratio m/m_{g} increases. In particular, in the Brownian limit (m/m_{g}â∞) the expressions of the non-Newtonian transport properties derived here are consistent with those previously obtained by considering a coarse-grained approach where the effect of gas phase on grains is through an effective force. Theoretical results are compared against computer simulations, showing an excellent agreement.
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The discovery of Orsay virus (OrV), the first virus infecting wild populations of Caenorhabditis elegans, has boosted studies of viral immunity pathways in this nematode. Considering the many advantages that C. elegans offers for fundamental research in host-pathogen interactions, this pathosystem has high potential to become a model system for experimental virus evolution studies. However, the evolutionary constraints - i.e, the balance between genetic variation, selection, drift and historical contingency- operating in this pathosystem have barely been explored. Here we describe for the first time an evolution experiment of two different OrV strains in C. elegans. Comparison of the two ancestral strains showed differences in infectivity and sequence, and highlighted the importance of consistently normalize viral inocula for meaningful comparisons among strains. After 10 serial passages of evolution, we report slight changes in infectivity and non-synonymous mutations fixed in the evolved viral populations. In addition, we observed numerous minor variants emerging in the viral population. These minor variants were not randomly distributed along the genome but concentrated in polymorphic genomic regions. Overall, our work established the grounds for future experimental virus evolution studies using Caenorhabditis nematodes.
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BACKGROUND: Narrowing, trauma, tumors, and systemic diseases can cause esophageal dysfunction. Severe cases resist traditional surgery, leading to long-term gastrostomy or jejunostomy tubes, affecting patients negatively. No established surgery ensures both airway and oral function with proper speech. This article introduces the oral-vestibule-enteral anastomosis (OVEA) technique, targeting patients with compromised epiglottic closure competence and loss of cervical esophagus, where conventional methods fall short. METHODS: Technique description study evaluated in 13 patients in a single tertiary referral center in Mexico City treated with OVEA from January 1990 to July 2023. RESULTS: Of the 13 patients (69% male; mean age, 37.14 ± 12.907 years), preoperative conditions included a mean body mass index of 17.78 ± 2.66 kg/m2, 46% with previous abdominal surgeries, and 31% with a smoking history. After OVEA, complications affected 46%, primarily pneumonia (23%), abscess formations (15%), intestinal necrosis (8%), and airway fistula (8%). Reoperation was needed in 38%, addressing functionality loss, necrosis, stenosis, and jawbone remodeling. No fatalities occurred within the first 6 months after surgery; 84% had successful gastrostomy tube removal, and 8% retained a tracheostomy tube. Currently 13 patients (92%) use the OVEA as their main enteral route of feeding. CONCLUSION: The OVEA technique seems promising for cases involving esophageal loss or impaired epiglottic function, enhancing patients' quality of life by enabling oral feeding and restoring regular eating habits. Further research should focus on long-term results and identifying optimal candidates for this innovative surgical method.
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Recent studies have demonstrated that the mechanisms through which biopolymers like RNA interconvert between multiple folded structures are critical for their cellular functions. A major obstacle to elucidating these mechanisms is the lack of experimental approaches that can resolve these interconversions between functionally relevant biomolecular structures. Here, using a nano-electronic device with microsecond time resolution, we dissect the complete set of structural rearrangements executed by an ultra-stable RNA, the UUCG stem-loop, at the single-molecule level. We show that the stem-loop samples at least four conformations along two folding pathways leading to two distinct folded structures, only one of which has been previously observed. By modulating its flexibility, the stem-loop can adaptively select between these pathways, enabling it to both fold rapidly and resist unfolding. This paradigm of stabilization through compensatory changes in flexibility broadens our understanding of stable RNA structures and is expected to serve as a general strategy employed by all biopolymers.
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Eukaryotic translation initiation factor (eIF) 3 is a multi-subunit protein complex that binds both ribosomes and messenger RNAs (mRNAs) in order to drive a diverse set of mechanistic steps during translation. Despite its importance, a unifying framework explaining how eIF3 performs these numerous activities is lacking. Using single-molecule light scattering microscopy, we demonstrate that Saccharomyces cerevisiae eIF3 is an equilibrium mixture of the full complex, subcomplexes, and subunits. By extending our microscopy approach to an in vitro reconstituted eIF3 and complementing it with biochemical assays, we define the subspecies comprising this equilibrium and show that, rather than being driven by the full complex, mRNA binding by eIF3 is instead driven by the eIF3a subunit within eIF3a-containing subcomplexes. Our findings provide a mechanistic model for the role of eIF3 in the mRNA recruitment step of translation initiation and establish a mechanistic framework for explaining and investigating the other activities of eIF3.
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The incidence of candidemia in healthcare centers is associated with high morbidity and mortality. Frequency varies significantly among regions, with some species being more prevalent than others in Latin America. In this study, 191 clinical Candida isolates were collected from a major hospital in Ecuador from January 2019 to February 2020 aiming to assess their prevalence and distribution. After data processing, 168 isolates characterized by the VITEK 2 system were subsequently identified by ITS sequencing. Results showed diverse Candida species distributions, with C. albicans and C. tropicalis being the most prevalent across different clinical sources. In hospitalized individuals, C. tropicalis (38%) and C. albicans (37%) were the most prevalent, followed by, C. parapsilosis (16%), C. glabrata (5%), and other non-Candida albicans (NCA) species (6%). Conversely, C. parapsilosis (48%), C. albicans (20%), and C. glabrata (14%), associated with candidemia, were the most common in blood and CSF. Additionally, uncommon NCA species such as C. haemulonii, C. kefyr, and C. pelliculosa were identified in Ecuador for the first time. Discrepancies in species identification were observed between the VITEK 2 system and ITS sequencing, coinciding at 85%. This highlights the need for ongoing surveillance and identification efforts in Ecuador's clinical and epidemiological settings.
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OBJECTIVE: Social media allows individuals to access a vast amount of health-related information immediately and anonymously, a fact that is turning these platforms into one of the primary sources of reference in this area, especially for younger generations. Given this reality, the objective of determining the impact of social media on digital health literacy in the general Spanish population was proposed. METHODS: A cross-sectional descriptive study was carried out in 2023. Using a non-probabilistic sampling, the population residing in Spain, over eighteen years old, and users of social networks were included, obtaining a sample of 1,307 participants. An adaptation of the validated eHEALS questionnaire on digital health literacy was used. This questionnaire, created in Microsoft Forms, was disseminated through an anonymous link via the research team's social networks and collaborators. A descriptive and inferential statistical analysis was performed using SPSS 22.0, assuming a significance level with a value of p<0.05. RESULTS: All participants affirmed having consumed health information through social networks, but 72.1% stated they had actively used these platforms to search for this health information. Regarding digital health literacy, a median score of 24 out of 40 points was obtained on the questionnaire, being significantly higher among those who claimed to use social networks as a source of health information (p=0.0001). CONCLUSIONS: Actively employing social media as a source of health information is associated with a higher level of digital health literacy.
OBJECTIVE: Las redes sociales permiten a las personas acceder de manera inmediata y anónima a una cantidad ingente de información sobre aspectos de salud, hecho que está provocando que se estén convirtiendo en una de las fuentes de referencia en este ámbito, sobre todo para las generaciones más jóvenes. Atendiendo a esta realidad se planteó el objetivo de determinar el impacto de las redes sociales en la alfabetización digital en salud en la población general española. METHODS: Se realizó un estudio descriptivo transversal en el año 2023. Mediante un muestreo no probabilístico, se incluyó población residente en España, mayor de dieciocho años y usuaria de redes sociales, obteniendo una muestra de 1.307 participantes. Se utilizó una adaptación del cuestionario validado eHEALS sobre alfabetización digital en salud. Dicho cuestionario, elaborado en Microsoft Forms, fue difundido mediante un enlace anónimo a través de las redes sociales del equipo investigador y colaboradores. Se realizó un análisis estadístico descriptivo e inferencial mediante SPSS 22.0, asumiendo un nivel de significación con un valor de p<0,05. RESULTS: La totalidad de los participantes afirmaron haber consumido información sobre salud a través de redes sociales, pero fue el 72,1% el que afirmó haber usado estas plataformas activamente para buscar esta información sobre salud. Con respecto a la alfabetización digital en salud, se obtuvo una puntuación mediana en el cuestionario de 24 sobre 40 puntos, siendo significativamente mayor entre los que afirmaron usar las redes sociales como fuente de información sobre salud (p=0,0001). CONCLUSIONS: Emplear de manera activa las redes sociales como fuente de información sobre salud parece tener relación con un mayor nivel de alfabetización digital en salud.
Subject(s)
Health Literacy , Social Media , Humans , Spain , Cross-Sectional Studies , Male , Female , Adult , Middle Aged , Social Media/statistics & numerical data , Young Adult , Aged , Adolescent , Consumer Health Information/methods , Surveys and Questionnaires , Social Networking , Information SourcesABSTRACT
C. elegans animals with a compromised pharynx accumulate bacteria in their intestinal lumen and activate a transcriptional response that includes anti-bacterial response genes. In this study, we demonstrate that animals with defective pharynxes are resistant to Orsay virus (OrV) infection. This resistance is observed for animals grown on Escherichia coli OP50 and on Comamonas BIGb0172, a bacterium naturally associated with C. elegans . The viral resistance observed in defective-pharynx mutants does not seem to result from constitutive transcriptional immune responses against viruses. OrV resistance is also observed in mutants with defective defecation, which share with the pharynx-defective perturbations in the regulation of their intestinal contents and altered lipid metabolism. The underlying mechanisms of viral resistance in pharynx- and defecation-defective mutants remain elusive.
ABSTRACT
The Boltzmann kinetic equation for dilute granular suspensions under simple (or uniform) shear flow (USF) is considered to determine the non-Newtonian transport properties of the system. In contrast to previous attempts based on a coarse-grained description, our suspension model accounts for the real collisions between grains and particles of the surrounding molecular gas. The latter is modeled as a bath (or thermostat) of elastic hard spheres at a given temperature. Two independent but complementary approaches are followed to reach exact expressions for the rheological properties. First, the Boltzmann equation for the so-called inelastic Maxwell models (IMM) is considered. The fact that the collision rate of IMM is independent of the relative velocity of the colliding spheres allows us to exactly compute the collisional moments of the Boltzmann operator without the knowledge of the distribution function. Thanks to this property, the transport properties of the sheared granular suspension can be exactly determined. As a second approach, a Bhatnagar-Gross-Krook (BGK)-type kinetic model adapted to granular suspensions is solved to compute the velocity moments and the velocity distribution function of the system. The theoretical results (which are given in terms of the coefficient of restitution, the reduced shear rate, the reduced background temperature, and the diameter and mass ratios) show, in general, a good agreement with the approximate analytical results derived for inelastic hard spheres (IHS) by means of Grad's moment method and with computer simulations performed in the Brownian limiting case (m/mgâ∞, where mg and m are the masses of the particles of the molecular and granular gases, respectively). In addition, as expected, the IMM and BGK results show that the temperature and non-Newtonian viscosity exhibit an S shape in a plane of stress-strain rate (discontinuous shear thickening, DST). The DST effect becomes more pronounced as the mass ratio m/mg increases.
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BACKGROUND: Radicular cyst is a lesion of odontogenic origin that arises from epithelial remains due to periapical periodontitis caused by inflammatory reactions generated at the apex of affected teeth with infected or necrotic pulps. The therapeutic management of radicular cysts is controversial. There is only one case report of enucleation of a radicular cyst managed with microsurgery and apicoectomy, but without the use of the guided tissue regeneration (GTR) technique in the same surgical procedure. The present clinical case describes the management of a radicular cyst with microsurgical approach, performance of an apicoectomy of the tooth associated with the entity, application of GTR technique, use of a resorbable membrane of type I bovine collagen, and bovine xenograft. CASE SUMMARY: A 68-year-old patient presented with a radicular cyst from an upper lateral incisor. The microsurgical management used was aimed at enucleating the chemical membrane, performing apicoectomy of the tooth along with careful and precise retrograde filling, and implementing GTR technique using a resorbable collagen membrane and bovine xenograft. The diagnosis of radicular cyst was confirmed using histopathological analysis. The patient underwent follow-up evaluations at 10 and 30 d postoperatively. At 4 months postoperative evaluation, she remained asymptomatic, and radiographs showed significant periapical healing with adequate bone formation. CONCLUSION: These results suggest that microsurgical management using the GTR technique with collagen membrane and xenograft, contributes to bone regeneration.
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OBJECTIVE: This study aimed to explore perceived barriers to early diagnosis and management of oral cancer, as well as potential pathways for improvement in Latin America and the Caribbean (LAC). METHODS: This cross-sectional study used a self-administered online questionnaire created via the Research Electronic Data Capture platform. The survey was distributed to health professionals trained in Oral Medicine, Oral Pathology, Oral and Maxillofacial Surgery, and Dentists with clinical and academic expertise in oral potentially malignant disorder (OPMD) and oral cancer. Data obtained were systematically organized and analyzed descriptively using Microsoft Excel. RESULTS: Twenty-three professionals from 21 LAC countries participated. Major barriers included the limited implementation of OPMD and oral cancer control plans (17.4%), low compulsory reporting for OPMD (8.7%) and oral cancer (34.8%), unclear referral pathways for OPMD (34.8%) and oral cancer (43.5%), and a shortage of trained professionals (8.7%). Participants endorsed the utility of online education (100%) and telemedicine (91.3%). CONCLUSION: The survey highlights major perceived barriers to early diagnosis and management of OPMD and oral cancer in LAC, as well as potential avenues for improvement.
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The model organism Caenorhabditis elegans is susceptible to infection by obligate intracellular pathogens, specifically microsporidia and viruses. These intracellular pathogens infect intestinal cells, or, for some microsporidia, epidermal cells. Strikingly, intestinal cell infections by viruses or microsporidia trigger a common transcriptional response, activated in part by the ZIP-1 transcription factor. Among the strongest activated genes in this response are ubiquitin-pathway members and members of the pals family, an intriguing gene family with cross-regulations of different members of genomic clusters. Some of the induced genes participate in host defense against the pathogens, for example through ubiquitin-mediated inhibition. Other mechanisms defend the host specifically against viral infections, including antiviral RNA interference and uridylation. These various immune responses are altered by environmental factors and by intraspecific genetic variation of the host. These pathogens were first isolated 15 years ago and much remains to be discovered using C. elegans genetics; also, other intracellular pathogens of C. elegans may yet to be discovered.
Subject(s)
Caenorhabditis elegans Proteins , Microsporidia , Viruses , Animals , Caenorhabditis elegans , Host-Pathogen Interactions/physiology , Caenorhabditis elegans Proteins/genetics , UbiquitinABSTRACT
A longitudinal ophthalmic dataset was used to investigate multi-modal machine learning (ML) models incorporating patient demographics and history, clinical measurements, optical coherence tomography (OCT), and visual field (VF) testing in predicting glaucoma surgical interventions. The cohort included 369 patients who underwent glaucoma surgery and 592 patients who did not undergo surgery. The data types used for prediction included patient demographics, history of systemic conditions, medication history, ophthalmic measurements, 24-2 VF results, and thickness measurements from OCT imaging. The ML models were trained to predict surgical interventions and evaluated on independent data collected at a separate study site. The models were evaluated based on their ability to predict surgeries at varying lengths of time prior to surgical intervention. The highest performing predictions achieved an AUC of 0.93, 0.92, and 0.93 in predicting surgical intervention at 1 year, 2 years, and 3 years, respectively. The models were also able to achieve high sensitivity (0.89, 0.77, 0.86 at 1, 2, and 3 years, respectively) and specificity (0.85, 0.90, and 0.91 at 1, 2, and 3 years, respectively) at an 0.80 level of precision. The multi-modal models trained on a combination of data types predicted surgical interventions with high accuracy up to three years prior to surgery and could provide an important tool to predict the need for glaucoma intervention.
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BACKGROUND: COVID-19 emerged in late 2019 and has occasioned more than 765 millions cumulative cases and 6.9 millions of deaths globally. Notably, around 70% of patients with severe COVID-19 are men. Therefore, it is to be presumed that women have a hormonal protector factor in inflammation and ACE2 expression. On the other hand, oral health status, and local microbiome can be key factors to respiratory viral infections control. Nevertheless, it has been poorly investigated. In our study 20 premenopausal, 18 postmenopausal and 22 men with COVID-19 were included. Oral health status, viral load, lingual ACE2 expression, as well as microbiome, estrogens and cytokines in saliva were analyzed. RESULTS: Our results showed a lower expression of ACE2 in tongue cells of postmenopausal compared with premenopausal (p = 0.05), and a strong negative correlation between saliva estrogen and viral load (r = -0.76; p = 0.001). Respect to IFN-γ (p = 0.05), IL-1ß, TNF-α, IL-18, and IL-23 levels were increased in postmenopausal. Oral microbiome signature of premenopausal was characterized by Prevotella melaninogenica (Log2 = 26.68; p = 1.34e-10), Haemophilus (Log2 = 23.99; p = 2.96e-9), and Alloprevotella (Log2 = 7.92; p = 0.0001). On the other hand, Leptotrichia (Log2 = -18.74; p = 0.001), Tanerella (Log2 = -17.08; p = 0.004), and Clostridiales (Log2 = -2.88; p = 0.04) represented the poor oral health group compared with the adequate group which was enriched with the commensal microorganism Neisseria perflava (Log2 = 26.70; p = 1.74e-7). Furthermore, the high viral load group was characterized by Prevotella nanceiensis (Log2 = 19.60; p = 6.06e-8), Prevotella melaninogenica (Log2 = 21.45; p = 9.59e-6), Alloprevotella (Log2 = 23.50; p = 2.70e-7) and bacteria from the red complex Porphyromonas endodentalis (Log2 = 21.97; p = 1.38e-7). CONCLUSIONS: Postmenopausal and men have a poor oral health status which could be related to a detrimental progression of COVID-19 also linked to a lower expression of ACE2, lower saliva estrogen levels and oral dysbiosis. Nevertheless, functional studies are required for a deeper knowledge.
Subject(s)
COVID-19 , Microbiota , Male , Humans , Female , Oral Health , Angiotensin-Converting Enzyme 2 , Estrogens , BacteroidetesABSTRACT
Microbes associated with an organism can significantly modulate its susceptibility to viral infections, but our understanding of the influence of individual microbes remains limited. The nematode Caenorhabditis elegans is a model organism that in nature inhabits environments rich in bacteria. Here, we examine the impact of 71 naturally associated bacteria on C. elegans susceptibility to its only known natural virus, the Orsay virus. Our findings reveal that viral infection of C. elegans is significantly influenced by monobacterial environments. Compared to an Escherichia coli environmental reference, the majority of tested bacteria reduced C. elegans susceptibility to viral infection. This reduction is not caused by virion degradation or poor animal nutrition by the bacteria. The repression of viral infection by the bacterial strains Chryseobacterium JUb44 and Sphingobacterium BIGb0172 does not require the RIG-I homolog DRH-1, which is known to activate antiviral responses such as RNA interference and transcriptional regulation. Our research highlights the necessity of considering natural biotic environments in viral infection studies and opens the way future research on host-microbe-virus interactions.
Subject(s)
Caenorhabditis elegans Proteins , Virus Diseases , Viruses , Animals , Caenorhabditis elegans/genetics , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , RNA Interference , Virus Diseases/genetics , Viruses/metabolismABSTRACT
Time-dependent single-molecule experiments contain rich kinetic information about the functional dynamics of biomolecules. A key step in extracting this information is the application of kinetic models, such as hidden Markov models (HMMs), which characterize the molecular mechanism governing the experimental system. Unfortunately, researchers rarely know the physicochemical details of this molecular mechanism a priori, which raises questions about how to select the most appropriate kinetic model for a given single-molecule data set and what consequences arise if the wrong model is chosen. To address these questions, we have developed and used time-series modeling, analysis, and visualization environment (tMAVEN), a comprehensive, open-source, and extensible software platform. tMAVEN can perform each step of the single-molecule analysis pipeline, from preprocessing to kinetic modeling to plotting, and has been designed to enable the analysis of a single-molecule data set with multiple types of kinetic models. Using tMAVEN, we have systematically investigated mismatches between kinetic models and molecular mechanisms by analyzing simulated examples of prototypical single-molecule data sets exhibiting common experimental complications, such as molecular heterogeneity, with a series of different types of HMMs. Our results show that no single kinetic modeling strategy is mathematically appropriate for all experimental contexts. Indeed, HMMs only correctly capture the underlying molecular mechanism in the simplest of cases. As such, researchers must modify HMMs using physicochemical principles to avoid the risk of missing the significant biological and biophysical insights into molecular heterogeneity that their experiments provide. By enabling the facile, side-by-side application of multiple types of kinetic models to individual single-molecule data sets, tMAVEN allows researchers to carefully tailor their modeling approach to match the complexity of the underlying biomolecular dynamics and increase the accuracy of their single-molecule data analyses.
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BACKGROUND: In the different published studies, there is no consensus on the efficacy of virtual reality as an adjuvant treatment of mood states. AIM: The aim of this study is to evaluate the impact of no immersive virtual reality with the Nintendo Switch device in rehabilitation treatment on mood, anxiety and depression in stroke patients admitted to neurorehabilitation units. METHODS: Fifty-eight patients admitted to neurorehabilitation units underwent a 1:3 multicentre randomised clinical trial. The intervention group consisted of 17 patients and the control group of 41 patients. The intervention group performed 6 virtual reality sessions together with the conventional treatment, and the control group performed only the conventional rehabilitation sessions. Primary and secondary clinical outcomes were measured before and six weeks after the intervention. RESULTS: Comparing the intervention group and control group, the anxiety levels of the intervention group decreased compared to the results observed in the control group (p = 0.01), as did the dependence of the intervention group (0.015). On the other hand, the results obtained after the intervention by the control group for anxiety (0.479) and depression (0.292) were not statistically significant. CONCLUSION: Rehabilitation VR used as an adjuvant treatment to conventional treatment has a beneficial impact on the neurological status and state of anxiety of stroke patients admitted to neurorehabilitation units. TRIAL REGISTRATION: Registered in the https://clinicaltrials.gov/ repository (NTC NCT05143385). Protocol registration date 7 October 2021, retrospectively registered.
Subject(s)
Stroke Rehabilitation , Stroke , Video Games , Humans , Stroke Rehabilitation/methods , Depression/etiology , Depression/therapy , Stroke/complications , Stroke/therapy , Anxiety/etiology , Anxiety/therapyABSTRACT
Plant viruses account for enormous agricultural losses worldwide, and the most effective way to combat them is to identify genetic material conferring plant resistance to these pathogens. Aiming to identify genetic associations with responses to infection, we screened a large panel of Arabidopsis thaliana natural inbred lines for four disease-related traits caused by infection by A. thaliana-naïve and -adapted isolates of the natural pathogen turnip mosaic virus (TuMV). We detected a strong, replicable association in a 1.5 Mb region on chromosome 2 with a 10-fold increase in relative risk of systemic necrosis. The region contains several plausible causal genes as well as abundant structural variation, including an insertion of a Copia transposon into a Toll/interleukin receptor (TIR-NBS-LRR) coding for a gene involved in defense, that could be either a driver or a consequence of the disease-resistance locus. When inoculated with TuMV, loss-of-function mutant plants of this gene exhibited different symptoms than wild-type plants. The direction and severity of symptom differences depended on the adaptation history of the virus. This increase in symptom severity was specific for infections with the adapted isolate. Necrosis-associated alleles are found worldwide, and their distribution is consistent with a trade-off between resistance during viral outbreaks and a cost of resistance otherwise, leading to negative frequency-dependent selection.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Potyvirus , Humans , Arabidopsis/genetics , Potyvirus/genetics , Arabidopsis Proteins/genetics , Necrosis , Plant Diseases/geneticsABSTRACT
AIMS: Dipeptidyl peptidase 4 (DPP4) has been proposed as a coreceptor for SARS-CoV-2 cellular entry. Considering that type 2 diabetes mellitus (T2DM) has been identified as the most important risk factor for SARS-CoV-2, and that gliptins (DPP4 inhibitors) are a prescribed diabetic treatment, this study aims to unravel the impact of DPP4 in the intersection of T2DM/COVID-19. MATERIALS AND METHODS: We analyzed 189 serum human samples, divided into six clinical groups (controls, T2DM, T2DM + gliptins, COVID-19, COVID-19 + T2DM, and COVID-19 + T2DM + gliptins), measuring DPP4 protein concentration and activity by Western blot, ELISA, and commercial activity kits. The obtained results were verified in Huh-7 cellular models. KEY FINDINGS: Both DPP4 concentration and activity were decreased in COVID-19 patients, and as in T2DM patients, compared to controls. Despite these lower levels, the ratio of DPP4 activity/concentration in COVID-19 sera was the highest (0.782 ± 0.289 µU/ng vs. 0.547 ± 0.050 µU/ng in controls, p < 0.0001), suggesting a compensating mechanism in these patients. Supernatants of Huh-7 cells incubated with COVID-19 serum showed a consistent and significantly lower DPP4 concentration and activity. Furthermore, COVID-19 + T2DM + gliptins patients showed a higher serum DPP4 concentration and activity than T2DM + gliptin subjects (p < 0.05), indicating that sera from COVID-19 convalescents interfere with gliptins. SIGNIFICANCE: Either SARS-CoV-2 or some metabolites present in the sera of COVID-19-convalescent patients interact with soluble DPP4 or even gliptins themselves since the inhibitory effect of gliptins on DPP4 activity is being prevented. The interactions between DPP4, gliptins, and SARS-CoV-2 should be further elucidated to reveal the mechanism of action for these interesting observations.
Subject(s)
COVID-19 , Diabetes Mellitus, Type 2 , Dipeptidyl-Peptidase IV Inhibitors , Humans , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/drug therapy , Dipeptidyl-Peptidase IV Inhibitors/pharmacology , Dipeptidyl-Peptidase IV Inhibitors/therapeutic use , Dipeptidyl Peptidase 4/metabolism , SARS-CoV-2/metabolismABSTRACT
Time-dependent single-molecule experiments contain rich kinetic information about the functional dynamics of biomolecules. A key step in extracting this information is the application of kinetic models, such as hidden Markov models (HMMs), which characterize the molecular mechanism governing the experimental system. Unfortunately, researchers rarely know the physico-chemical details of this molecular mechanism a priori, which raises questions about how to select the most appropriate kinetic model for a given single-molecule dataset and what consequences arise if the wrong model is chosen. To address these questions, we have developed and used time-series Modeling, Analysis, and Visualization ENvironment (tMAVEN), a comprehensive, open-source, and extensible software platform. tMAVEN can perform each step of the single-molecule analysis pipeline, from pre-processing to kinetic modeling to plotting, and has been designed to enable the analysis of a single-molecule dataset with multiple types of kinetic models. Using tMAVEN, we have systematically investigated mismatches between kinetic models and molecular mechanisms by analyzing simulated examples of prototypical single-molecule datasets exhibiting common experimental complications, such as molecular heterogeneity, with a series of different types of HMMs. Our results show that no single kinetic modeling strategy is mathematically appropriate for all experimental contexts. Indeed, HMMs only correctly capture the underlying molecular mechanism in the simplest of cases. As such, researchers must modify HMMs using physico-chemical principles to avoid the risk of missing the significant biological and biophysical insights into molecular heterogeneity that their experiments provide. By enabling the facile, side-by-side application of multiple types of kinetic models to individual single-molecule datasets, tMAVEN allows researchers to carefully tailor their modeling approach to match the complexity of the underlying biomolecular dynamics and increase the accuracy of their single-molecule data analyses.