Dynamical classic limit: Dissipative vs conservative systems.

We analyze the nonlinear dynamics of a quartic semiclassical system able to describe the interaction of matter with a field. We do it in both dissipative and conservative scenarios. In particular, we study the classical limit of both frameworks and compare the associated features. In the two environments, we heavily use a system's invariant, related to the Uncertainty Principle, that helps to determine how the dynamics tends to the pertinent classical limit. We exhibit the convergence to the classical limit and also verify that the Uncertainty Principle is complied with during the entire process, even in the presence of dissipation.

Neutralizing Ability of a Single Domain VNAR Antibody: In Vitro Neutralization of SARS-CoV-2 Variants of Concern.

Severe Acute Respiratory Syndrome Coronavirus 2 is the causal pathogen of coronavirus disease 2019 (COVID-19). The emergence of new variants with different mutational patterns has limited the therapeutic options available and complicated the development of effective neutralizing antibodies targeting the spike (S) protein. Variable New Antigen Receptors (VNARs) constitute a neutralizing antibody technology that has been introduced into the list of possible therapeutic options against SARS-CoV-2. The unique qualities of VNARs, such as high affinities for target molecules, capacity for paratope reformatting, and relatively high stability, make them attractive molecules to counteract the emerging SARS-CoV-2 variants. In this study, we characterized a VNAR antibody (SP240) that was isolated from a synthetic phage library of VNAR domains. In the phage display, a plasma with high antibody titers against SARS-CoV-2 was used to selectively displace the VNAR antibodies bound to the antigen SARS-CoV-2 receptor binding domain (RBD). In silico data suggested that the SP240 binding epitopes are located within the ACE2 binding interface. The neutralizing ability of SP240 was tested against live Delta and Omicron SARS-CoV-2 variants and was found to clear the infection of both variants in the lung cell line A549-ACE2-TMPRSS2. This study highlights the potential of VNARs to act as neutralizing antibodies against emerging SARS-CoV-2 variants.

Exactly solvable SIR models, their extensions and their application to sensitive pandemic forecasting.

The classic SIR model of epidemic dynamics is solved completely by quadratures, including a time integral transform expanded in a series of incomplete gamma functions. The model is also generalized to arbitrary time-dependent infection rates and solved explicitly when the control parameter depends on the accumulated infections at time t. Numerical results are presented by way of comparison. Autonomous and non-autonomous generalizations of SIR for interacting regions are also considered, including non-separability for two or more interacting regions. A reduction of simple SIR models to one variable leads us to a generalized logistic model, Richards model, which we use to fit Mexico's COVID-19 data up to day number 134. Forecasting scenarios resulting from various fittings are discussed. A critique to the applicability of these models to current pandemic outbreaks in terms of robustness is provided. Finally, we obtain the bifurcation diagram for a discretized version of Richards model, displaying period doubling bifurcation to chaos.

Turing instability conditions in confined systems with an effective position-dependent diffusion coefficient.

We study a reaction-diffusion system within a long channel in the regime in which the projected Fick-Jacobs-Zwanzig operator for confined diffusion can be used. We found that under this approximation, Turing instability conditions can be modified due to the channel geometry. The dispersion relation, range of unstable modes where pattern formation occurs, and spatial structure of the patterns itself change as functions of the geometric parameters of the channel. This occurs for the three channels analyzed, for which the values of the projected operators can be found analytically. For the reaction term, we use the well-known Schnakenberg kinetics.

Non-invasive brain stimulation for fine motor improvement after stroke: a meta-analysis.

The aim of this study was to determine whether non-invasive brain stimulation (NIBS) techniques improve fine motor performance in stroke. We searched PubMed, EMBASE, Web of Science, SciELO and OpenGrey for randomized clinical trials on NIBS for fine motor performance in stroke patients and healthy participants. We computed Hedges' g for active and sham groups, pooled data as random-effects models and performed sensitivity analysis on chronicity, montage, frequency of stimulation and risk of bias. Twenty-nine studies (351 patients and 152 healthy subjects) were reviewed. Effect sizes in stroke populations for transcranial direct current stimulation and repeated transcranial magnetic stimulation were 0.31 [95% confidence interval (CI), 0.08-0.55; P = 0.010; Tau2 , 0.09; I2 , 34%; Q, 18.23; P = 0.110] and 0.46 (95% CI, 0.00-0.92; P = 0.05; Tau2 , 0.38; I2 , 67%; Q, 30.45; P = 0.007). The effect size of non-dominant healthy hemisphere transcranial direct current stimulation on non-dominant hand function was 1.25 (95% CI, 0.09-2.41; P = 0.04; Tau2 , 1.26; I2 , 93%; Q, 40.27; P < 0.001). Our results show that NIBS is associated with gains in fine motor performance in chronic stroke patients and healthy subjects. This supports the effects of NIBS on motor learning and encourages investigation to optimize their effects in clinical and research settings.

Evolution of incidence and geographical distribution of Chagas disease in Mexico during a decade (2007-2016).

Chagas disease, whose aetiological agent is the protozoan Trypanosoma cruzi, mainly occurs in Latin America. In order to know the epidemiology and the geographical distribution of this disease in Mexico, the present work analyses the national surveillance data (10 years) for Chagas disease issued by the General Directorate of Epidemiology (GDE). An ecological analysis of Chagas disease (2007-2016) was performed in the annual reports issued by the GDE in Mexico. The cases and incidence were classified by year, state, age group, gender and seasons. A national distribution map showing Chagas disease incidence was generated. An increase of new cases was identified throughout the country (rates from 0.37 to 0.81 per 100 000 inhabitants). Of the total cases accumulated (7388), the major cases were attributed to the states of Veracruz, Chiapas, Quintana Roo, Oaxaca, Morelos and Yucatán. The analysis per age groups and gender revealed that, in most age groups, the incidence was higher in the male population. The most number of cases was identified in spring and summer; a direct relationship between the environmental temperature increase and the number of new cases was identified. The analysis showed that the rate of Chagas disease increased presumably due to state programmes; the search for new cases has expanded and we speculate that the disease is associated with occupational activities. These results summarise and recall how important it is to implement the monitoring of Chagas disease mainly in south states of the Mexican Republic in order to implement strategies to control this disease.

Measurement of cerebrospinal fluid lactate levels in pediatric patients with suspected ventriculoperitoneal shunt infection: A retrospective cohort study.

INTRODUCTION: Ventriculoperitoneal shunt (VPS) infection is a severe complication. Early diagnosis could help to decrease morbidity and treatment costs. Lactate has been used for the diagnosis of other central nervous system infections. The aim of this study is to determine the usefulness of lactate for the diagnosis of VPS infection. METHODOLOGY: Retrospective cohort study. Lactate was measured in patients who consulted with VPS dysfunction between May 2019 and May 2022. Mean were compared according to culture results. A Receiver Operating Characteristic (ROC) curve was performed to determine the appropriate cut-off point. RESULT: Lactate has a high negative predictive value but a low positive predictive value for the diagnosis of ventriculitis.

The role of metabolic and bariatric surgery on the obesity pandemic in Latin America: A review of current practices and future directions.

Latin America faces a significant public health challenge due to the high prevalence of obesity and its associated diseases. Metabolic and bariatric surgery is effective and safe to treat obesity when other treatments fail; however, its implementation in Latin America remains unsatisfactory. This review explores the current status, challenges, and innovations of metabolic and bariatric surgery in Latin America. We searched peer-reviewed journals in English and Spanish for relevant articles published between 1998 and 2023. We found that more than 20% of the Latin American population is affected by obesity. Unfortunately, only a limited number of patients have access to metabolic and bariatric surgery due to high cost, limited availability, and shortage of specialists. The review found that ongoing clinical trials are being conducted in Brazil, Mexico, Chile, and Venezuela, indicating some regional progress. However, published studies remain low in number compared with other regions. Furthermore, we summarized the clinical outcomes, risks, and perioperative assessments associated with metabolic and bariatric surgery. We discussed potential strategies to enhance the availability and affordability of this intervention. This review emphasizes the significance of metabolic and bariatric surgery in addressing the obesity pandemic, specifically for Latin America, and proposes directions for future research and innovation.

The Relationship Between Myocardial Infarction and Estrogen Use: A Literature Review.

This thorough literature evaluation was prompted by significant research into the complex interactions between estrogen use and myocardial infarction (MI). Estrogen has fascinated researchers because of its possible cardioprotective benefits and its impact on cardiovascular health. In order to clarify the connection between estrogen use and the risk of MI, this review critically examines the body of prior evidence. This review focuses on estrogen and its pivotal role in cardiovascular health, concentrating on lipid metabolism, vasodilation, inflammation, and endothelial function. It examines contentious data about estrogen therapy's heart-protective effects, taking into account age, initiation timing, dosage, and dosage of administration. Genetic and epigenetic influences on MI risk among estrogen users highlight intricate, personalized estrogen effects. The conclusion summarizes the main findings and emphasizes the need for an all-encompassing strategy for initiating and managing estrogen medication. It is crucial to consider patient-specific traits and risk factors to successfully customize treatment regimens. This review sheds vital light on the potential directions for better cardiovascular treatment for postmenopausal women by shedding light on the complex link between estrogen use and myocardial infarction. The review also identifies research gaps and future objectives in this area, highlighting the demand for novel medicines and individualized strategies to improve cardiovascular outcomes.

Processed meat consumption and risk of cancer: a multisite case-control study in Uruguay.

BACKGROUND: The role of processed meat in the aetiology of several cancers was explored in detail. METHODS: In the time period 1996-2004, a multisite case-control study was conducted in Montevideo, Uruguay. The study included 6 060 participants (3 528 cases and 2 532 controls) corresponding to cancers of the oral cavity, pharynx, oesophagus, stomach, colon, rectum, larynx, lung, female breast, prostate, urinary bladder, and kidney (renal cell carcinoma only). RESULTS: The highest odds ratios (ORs) were positively associated with cancers of the colon, rectum, stomach, oesophagus, and lung. With the exception of renal cell carcinoma, the remaining cancer sites were significantly associated with elevated risks for processed meat consumption. Furthermore, mortadella, salami, hot dog, ham, and salted meat were strongly associated with risk of several cancer sites. CONCLUSION: It could be concluded that processed meat intake could be a powerful multiorgan carcinogen.

[Deficient lactose digestion and intolerance in a group of patients with chronic nonspecific ulcerative colitis: a controlled, double-blind, cross-over clinical trial]. / Digestión deficiente e intolerancia a lactosa en un grupo de enfermos con colitis ulcerativa crónica inespecífica: Ensayo clínico controlado, cruzado y doblemente a ciegas.

INTRODUCTION: Despite the fact that the frequency of hypolactasia and lactose intolerance is similar in both chronic idiopathic ulcerative colitis patients and the general population, the elimination of dairy products from the patient's diet is a habitual recommendation. Hypolactasia is common in Mexico, but its relation to chronic idiopathic ulcerative colitis has not been established. AIMS: To evaluate lactose digestion and lactose intolerance in persons with chronic idiopathic ulcerative colitis. MATERIAL AND METHODS: Thirty-nine patients with confirmed chronic idiopathic ulcerative colitis diagnosis were included in the study (mean: 31 years, range: 15 to 38). Twenty-two patients presented with rectosigmoid involvement and the remaining patients with pancolitis. No patient showed inflammatory activity according to the Truelove-Witts criteria and all consumed dairy products before diagnosis. A prospective, controlled, double-blind, cross-over study was designed. Patients randomly received 12.5 g of lactose or maltose in 250 cc water- each test 72 hours apart - and ydrogen was measured in exhaled air before disaccharide ingestion and then every 30 minutes for 3 hours. Digestion was considered deficient when there was an increase in hydrogen of at least 20 ppm. Symptom intensities were evaluated by Visual Analog Scales before, during, and after the hydrogen test. Differences between the groups were contrasted with the Mann-Whitney U and the Wilcoxon tests. RESULTS: Eighteen patients (46%) presented with deficient lactose digestion. No significant differences were found in the symptoms, extension, or progression of chronic idiopathic ulcerative colitis between patients that could digest and those that could not digest lactose. No patient had symptom exacerbation with the disaccharides used. CONCLUSIONS: Lactose digestion deficiency frequency is similar in subjects with chronic idiopathic ulcerative colitis and in healthy individuals in Mexico. We do not know whether higher doses could have some effect, but symptoms in patients with inactive chronic idiopathic ulcerative colitis were not modified using 12.5 g of lactose/day.

Dietary folate intake and the risk of 11 types of cancer: a case-control study in Uruguay.

BACKGROUND: There is limited, but inconclusive, epidemiological evidence that high folate intake decreases the risk of colorectal and esophageal cancers. For other cancer sites, the evidence is even less consistent or extensive. MATERIALS AND METHODS: We conducted a case-control study of dietary folate intake and risk of 11 cancer sites in Uruguay between 1996 and 2004, including 3539 cancer cases and 2032 hospital controls. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of cancer associated with folate intake. RESULTS: In the multivariable model, there was a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.49, 95% CI 0.24-0.98), esophagus (OR = 0.29, 95% CI 0.14-0.60), upper aerodigestive tract (OR = 0.41, 95% CI 0.26-0.65), colorectum (OR = 0.42, 95% CI 0.23-0.76) and kidney (OR = 0.35, 95% CI 0.13-0.93) for the highest versus the lowest quartile of dietary folate intake. CONCLUSIONS: Our results not only confirm earlier findings of decreased risk of colorectal and esophageal cancers with a high dietary folate intake but also suggest decreased risk of several other cancers. However, we cannot exclude the possibility that residual confounding, multiple comparisons or other forms of bias could explain these results.

The role for intra-arterial chemotherapy for refractory retinoblastoma: a systematic review.

BACKGROUND: Intra-arterial chemotherapy is a new retinoblastoma treatment associated with high rates of globe salvage that has been widely adopted for primary treatment of retinoblastoma but is less frequently used as secondary treatment for refractory retinoblastoma. This systematic review aims to summarize the reported outcomes of intra-arterial chemotherapy for refractory retinoblastoma. METHODS: We conducted a systematic review of studies published on PubMed, Medline, and Embase from 2011 to 2021 reporting globe salvage rates following intra-arterial chemotherapy for secondary treatment of refractory retinoblastoma. RESULTS: Our search yielded 316 studies, and 24 met inclusion criteria. The 24 included studies were comprised of 1366 patients and 1757 eyes. Among these, 1184 (67%) eyes received secondary indication treatment, and globe salvage was achieved for 776 of these 1184 eyes (64%). Sixteen studies reported cannulation success rates from 71.8 to 100%. Pooled analysis of subjects revealed 21 patients (2.6%) with metastatic disease and 26 deaths (3%) during study follow-up periods (7-74 months). The most common ocular complications were vitreous hemorrhage (13.2%), loss of eyelashes (12.7%), and periocular edema (10.5%). The most common systemic complications were nausea/vomiting (20.5%), neutropenia (14.1%), fever (8.2%), and bronchospasm (6.2%). CONCLUSIONS: Intra-arterial chemotherapy is associated with high rates of globe salvage and low rates of serious complications in patients with refractory retinoblastoma. Unfortunately, current literature is predominantly comprised of retrospective case studies, and further high-quality evidence is necessary to inform clinical practice.

[Central nervous system infections associated with CSF shunt devices in children, at a national reference hospital]. / Infecciones del sistema nervioso central asociadas a dispositivos de derivación de LCR en niños, en un centro neuro-quirúrgico de referencia nacional.

BACKGROUND: Infections associated with CSF shunt devices are a frequent complication in their use. The most common is the presence of gram positive coccaceae, such as coagulase negative Staphylococcus (50% in some series) and Staphylococcus aureus. This complication adds morbidity and mortality to the neurosurgical patient, increasing hospital stay and treatment costs. AIM: To determine the incidence of infections associated with CSF shunt devices in a national referral center. METHODS: Retrospective, descriptive study. Information was collected on pediatric patients between 2018 and 2019. A descriptive and inferential statistical analysis was performed using the statistical language R 3.4.0 and RStudio 1.3.9. The cumulative incidence for each procedure was calculated, evaluating whether there were significant differences between them. This study was approved by the Pediatric Ethics Committee of the SSMO. RESULTS: In the period studied, 175 surgeries were performed. We found 19 cases of ventriculitis associated with ventriculoperitoneal derivative and 7 cases in ventricular-external derivative. The most frequent agents were grampositive coccaceae. It was not possible to identify significant risk factors.

Diagnostic yield of brush cytology for biliary stenosis during ERCP.

AIM: To evaluate the diagnostic yield of brush cytology for biliary strictures detected on ERCP when a systematic approach is used. PATIENTS AND METHODS: Data on 62 consecutive patients with a biliary stricture on ERCP were collected. Cytological samples were processed immediately after brushing in the endoscopy room, and all were analyzed by the same pathologist. For the statistical analysis specimens were classified as positive, negative, suspicious for malignancy (presence of atypias), and unsatisfactory for evaluation. Final diagnosis was based on either histopathologic (surgery or biopsies by other techniques) or clinical/radiographic diagnosis. RESULTS: A total of 71 cytological specimens were included. Definite diagnosis was malignancy in 49 samples, and benign stricture in 22. Three samples were excluded because of insufficient material or processing artifacts. The sensitivity of biliary brushing was 62% (95% CI 0.47-0.77), specificity was 100%, positive predictive value was 100%, and negative predictive value was 58% (95% CI 0.43-0.75). When suspicious samples were included as malignant, sensitivity was 67% (95% CI 0.54-0.81) without changes in the remaining parameters. Eight patients underwent more than one ERCP. Repeated brush cytology exams in these patients yielded a definitive diagnosis in every case. CONCLUSIONS: Brush cytology has intermediate sensitivity with a high specificity. A systematic approach with a dedicated pathologist and the inclusion of significant atypias as malignant results improves sensitivity. Due to its simplicity brush cytology should be performed in all cases of biliary strictures detected on ERCP, and in case of repeated ERCPs additional cytology brushings are recommended.

Membrane stress and torque induced by Frank's nematic textures: A geometric perspective using surface-based constraints.

An elastic membrane with embedded nematic molecules is considered as a model of anisotropic fluid membrane with internal ordering. By considering the geometric coupling between director field and membrane curvature, the nematic texture is shown to induce anisotropic stresses additional to Canham-Helfrich elasticity. Building upon differential geometry, analytical expressions are found for the membrane stress and torque induced by splaying, twisting, and bending of the nematic director as described by the Frank energy of liquid crystals. The forces induced by prototypical nematic textures are visualized on the sphere and on cylindrical surfaces.

Voluntary alcohol intake after noise exposure in adolescent rats: Hippocampal-related behavioral alterations.

Different physical or chemical agents, such as noise or alcohol, can induce diverse behavioral and biochemical alterations. Considering the high probability of young people to undergo consecutive or simultaneous exposures, the aim of the present work was to investigate in an animal model if noise exposure at early adolescence could induce hippocampal-related behavioral changes that might be modified after alcohol intake. Male Wistar rats (28-days-old) were exposed to noise (95-97 dB, 2 h). Afterwards, animals were allowed to voluntarily drink alcohol (10% ethanol in tap water) for three consecutive days, using the two-bottle free choice paradigm. After that, hippocampal-related memory and anxiety-like behavior tests were performed. Results show that whereas noise-exposed rats presented deficits in habituation memory, those who drank alcohol exhibited impairments in associative memory and anxiety-like behaviors. In contrast, exposure to noise followed by alcohol intake showed increases in exploratory and locomotor activities as well as in anxiety-like behaviors, unlike what was observed using each agent separately. Finally, lower levels of alcohol intake were measured in these animals when compared with those that drank alcohol and were not exposed to noise. Present findings demonstrate that exposure to physical and chemical challenges during early adolescence might induce behavioral alterations that could differ depending on the schedule used, suggesting a high vulnerability of rat developing brain to these socially relevant agents.

D-serine: a new word in the glutamatergic neuro-glial language.

Gliotransmission is a process in which astrocytes are dynamic elements that influence synaptic transmission and synaptogenesis. The best-known gliotransmitters are glutamate and ATP. However, in the past decade, it has been demonstrated that D-serine, a D-amino acid, acts as a gliotransmitter in glutamatergic synapses. The physiological relevance of D-serine is sustained by the way in which it modulates the action of glutamatergic neurotransmission, neuronal migration and long-term potentiation (LTP). In addition, the synthesis and degradation mechanisms of D-serine have been proposed as potential therapeutic targets for the treatment of Alzheimer's disease, schizophrenia and related disorders. In the present review, detailed information is provided about the physiological and physiopathological relevance of D-serine, including metabolic and regulation aspects.