Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in Sao Paulo State (Brazil)

BackgroundThe continuous SARS-CoV-2 transmission in several countries could contribute to the mutations appearance. The circulation of more virulent variants may increase the number of severe CoViD-19 needing hospital care and fatalities hugely. MethodsThe partial quarantine in Sao Paulo State and further relaxation associated with the mutations are explained by a mathematical model based on the CoViD-19 natural history encompassing the age-dependent fatality. The model parameters were fitted considering the observed data from Sao Paulo State. ResultsThe partial quarantine was explained by the less virulent SARS-CoV-2 transmission, but the relaxation alone could not explain the epidemic observed in Sao Paulo State. However, more virulent variants plus the transmission among isolated individuals explained the increased CoViD-19 fatalities. ConclusionsThe model described the CoViD-19 epidemic in Sao Paulo State by considering the partial quarantine, relaxation and mutations. The model provided a potential epidemiological scenario in the absence of mass vaccination.

Evaluating the trade-off between transmissibility and virulence of SARS-CoV-2 by mathematical modeling

BackgroundAt the beginning of 2020, SARS-CoV-2 spread to all continents, and since then, mutations have appeared in different regions of the world. The appearance of more virulent mutations leads to asseverate that they are also more transmissible. We analyzed the lower and higher virulent SARS-CoV-2 epidemics to establish a relationship between transmissibility and virulence based on a mathematical model. MethodsA compartmental mathematical model based on the CoViD-19 natural history encompassing the age-dependent fatality was applied to evaluate the SARS-CoV-2 transmissibility and virulence. The transmissibility was measured by the basic reproduction number R0 and the virulence by the proportion of asymptomatic individuals. The model parameters were fitted considering the observed data from Sao Paulo State. ResultsThe numbers of severe CoViD-19 and deaths are three times higher, but R0 is 25% lower in more virulent SARS-CoV-2 transmission than in a less virulent one. However, the number of more virulent SARS-CoV-2 transmitting individuals is 25% lower, mainly due to symptomatic individuals isolation, explaining the increased transmission in lower virulence. ConclusionsThe quarantine study in Sao Paulo State showed that the more virulent SARS-CoV-2 resulted in a higher number of fatalities but less transmissible than the less virulent one. One possible explanation for the number of deaths surpassing that predicted by the low virulent SARS-CoV-2 infection could be the transmission of more virulent variant(s).

The SIR model estimates incorrectly the basic reproduction number for the covid-19 epidemic

The transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) becomes pandemic but presents different incidences in the world. Mathematical models were formulated to describe the coronavirus disease 2019 (CoViD-19) epidemic in each country or region. At the beginning of the pandemic, many authors used the SIR (susceptible, infectious, and recovered compartments) and SEIR (including exposed compartment) models to estimate the basic reproduction number R0 for the CoViD-19 epidemic. These simple deterministic models assumed that the only available collection of the severe CoViD-19 cases transmitted the SARS-CoV-2 and estimated lower values for R0, ranging from 1.5 to 3.0. However, the major flaw in the estimation of R0 provided by the SIR and SEIR models was that the severe CoViD-19 patients were hospitalized, and, consequently, not transmitting. Hence, we proposed a more elaborate model considering the natural history of CoViD-19: the inclusion of asymptomatic, pre-symptomatic, mild and severe CoViD-19 compartments. The model also encompassed the fatality rate depending on age. This SEAPMDR model estimated R0 using the severe CoViD-19 data from Sao Paulo State (Brazil) and Spain, yielding higher values for R0, that is, 6.54 and 5.88, respectively. It is worth stressing that this model assumed that severe CoViD-19 cases were not participating in the SARS-CoV-2 transmission chain. Therefore, the SIR and SEIR models are not suitable to estimate R0 at the beginning of the epidemic by considering the isolated severe CoViD-19 data as transmitters.

Evaluating the impacts of release in Sao Paulo State (Brazil) on the epidemic of covid-19 based on mathematical model

To flatten the curve of the natural epidemic of covid-19, many countries adopted lockdown or isolation resulting in the containment of the SARS-CoV-2 transmission. However, an important question arises about the strategies of release of isolated persons to avoid overloaded hospitals and increased deaths. Sao Paulo State (Brazil) implemented the isolation of the population in non-essential activities on March 24, and the progressive flexibilization considering the characteristics of each location (release of the isolated population) initiated on June 15. A mathematical model based on the natural history of covid-19 was applied to describe the epidemiological scenario with isolation in Sao Paulo State, and assess the impact of release on the covid-19 epidemic. Using data collected from Sao Paulo State, we estimated the model parameters to obtain the curves of the epidemic, the number of deaths, and the clinical evolution of covid-19. The epidemic under isolation was the framework to evaluate the strategies of the release, that is, how these curves are changed with the release of isolated persons. We evaluated three strategies of release. First two strategies considered four releases in the isolated population in four equal proportions, but successive releases elapsed by 14 and 21 days. In each strategy the beginning of the release was on June 29 and July 13, when the effective reproduction number Ref was evaluated. The third strategy aimed at the protection of the elder subpopulation. We observed that the delay to begin the release and the increased elapse between successive releases resulted in a better scenario by decreasing severe covid-19 cases and, consequently, to avoid overloaded hospitals. We also observed that the release delayed to achieve lower values for Ref and infectious persons retarded in several months the quick increasing phase of the forthcoming epidemic. However, this epidemic can be flattened or even suppressed by isolation of infectious persons by mass testing and/or by rigid adoption of protective measures and social distancing.

Mathematical modeling of the transmission of SARS-CoV-2 '' Evaluating the impact of isolation in Sao Paulo State (Brazil) and lockdown in Spain associated with protective measures on the epidemic of covid-19

Coronavirus disease 2019 (covid-19), with the fatality rate in elder (60 years old or more) being much higher than young (60 years old or less) patients, was declared a pandemic by the World Health Organization on March 11, 2020. Taking into account this age-dependent fatality rate, a mathematical model considering young and elder subpopulations was formulated based on the natural history of covid-19 to study the transmission of the SARS-CoV-2. This model can be applied to study the epidemiological scenario resulting from the adoption of isolation or lockdown in many countries to control the rapid propagation of covid-19. We chose as examples the isolation adopted in Sao Paulo State (Brazil) in the early phase but not at the beginning of the epidemic, and the lockdown implemented in Spain when the number of severe covid-19 cases was increasing rapidly. Based on the data collected from Sao Paulo State and Spain, the model parameters were evaluated and we obtained higher estimation for the basic reproduction number R0 (9.24 for Sao Paulo State, and 8 for Spain) compared to the currently accepted estimation of R0 around 3. The model allowed to explain the flattening of the epidemic curves by isolation in Sao Paulo State and lockdown in Spain when associated with the protective measures (face mask and social distancing) adopted by the population. However, a simplified mathematical model providing lower estimation for R0 did not explain the flattening of the epidemic curves. The implementation of the isolation in Sao Paulo State before the rapidly increasing phase of the epidemic enlarged the period of the first wave of the epidemic and delayed its peak, which are the desirable results of isolation to avoid the overloading in the health care system.

Evaluating epidemiological scenarios of isolation and further releases considering protection actions to control transmission of CoViD-19 in Sao Paulo State, Brazil.

Sao Paulo State registered the first case of CoViD-19 on 26 February, the first death due to CoViD-19 on 16 March, and implemented the isolation of the population in non-essential activities on 24 March, which is programmed to end on 1 June. A mathematical model considering young (below 60 years old) and elder (above 60 years) subpopulations was formulated based on the natural history of CoViD-19 to study the transmission of the new coronavirus in Sao Paulo State, Brazil. This deterministic model used the data collected in Sao Paulo State to estimate the model parameters and to evaluate the effects of herd protection, that is, isolation and personal and collective protective measures. Based on the estimated parameters, we evaluated the scenarios of three releases divided in equal proportions elapsed by 14 days between releases, but beginning in three different times (the first release occurring on 1 and 23 June, and 6 July). We concluded that these three strategies of release are equivalent (little difference) in reducing the number of severe CoViD-19 if social behaviour does not change. However, if protective measures as using face mask and hygiene (washing hands, for instance) and social distancing could be massively disseminated in the population to decrease the transmission of CoViD-19 by 80%, we concluded that the health care system may not collapse with release.

Mathematical model describing CoViD-19 in Sao Paulo State, Brazil - Evaluating isolation as control mechanism and forecasting epidemiological scenarios of release

We formulated a mathematical model considering young (below 60 years old) and elder (above 60 years) subpopulations to describe the introduction and dissemination of new coronavirus epidemics in the Sao Paulo State, Brazil. From the data collected in Sao Paulo State, we estimated the model parameters and calculated the basic reproduction number as R0 = 6.828. Considering isolation as a control mechanism, we varied the releasing proportions of young and elder persons to assess their epidemiological impacts. The best scenarios were release of young persons, but maintaining elder persons isolated. To avoid the collapse of the health care system, the isolation must be at least 80%.

Estimación del número de reproducibilidad basal para la leishmaniasis tegumentar americana en dos localidades del nordeste de la Provincia de Salta, Argentina / Estimation of the basic reproducibility number for American tegumentary leishmaniasis in two sitesin northeastern Salta Province, Argentina

Un modelo matemático determinístico del tipo SIR para tres hospedadores es aplicado para analizar el proceso de transmisión de la leishmaniasis tegumentar americana, en las localidades Río Blanco y paraje Las Carmelitas, ubicadas en el Nordeste de la Provincia de Salta, Argentina, del mismo se deriva la expresión para el número de reproducibilidad basal Ro. Se implementa el modelo en ambiente MATLAB, en base a datos de las zonas endémicas se realizan simulaciones y se obtienen estimaciones numéricas de Ro. Para el caso de Río Blanco hemos obtenido el valor Ro = 4,689, mientras que para el paraje Las Carmelitas se obtuvo Ro = 1,948. Estudiando numéricamente el modelo también se estima la fuerza de infección, obteniendo para las localidades mencionadas 0,239 y 0,171 (unidad 1/año), respectivamente. Las simulaciones muestran que en la localidad de Río Blanco la fase endémica resulta más sostenida que la fase inter-epidémica presentada en el paraje Las Carmelitas. Las estimaciones obtenidas para estos parámetros epidemiológicos indican donde las instituciones del Ministerio de Salud Pública de la Provincia y de la Nación tendrán más dificultad para el control y la erradicación de la enfermedad.

A SIR-type deterministic mathematical model for three hosts is applied to analyze the transmission process for American tegumentary leishmaniasis in Río Blanco and Las Carmelitas, located in northeastern Salta Province, Argentina, and to derive the expression for the baseline reproducibility number Ro. The model is implemented in the MATLAB environment, and based on data from endemic areas, simulations are performed and numerical estimations of Ro are obtained. Río Blanco shows Ro = 4.689 and Las Carmelitas Ro = 1.948. By studying the model numerically, we also estimate the force of infection, namely 0.239 and 0.171 (unit 1/year), respectively. The simulations show that in Río Blanco, the endemic phase was more sustained than the inter-epidemic phase in Las Carmelitas. The estimations of these epidemiological parameters indicate where the Ministry of Health and Provincial Health Department will experience greater difficulty in controlling and eradicating the disease.

Influences of Particles on Pro-inflammatory Signalings in Pre-osteoclasts / 대한정형외과연구학회지

PURPOSE: To evaluate the roles of macrophages and their influences on the signal transduction in the periprosthetic osteolysis, the pro-inflammatory signals were analyzed in particles-stimulated macrophages. MATERIALS AND METHODS: Raw 264.7 cell line derived from mice macrophages was used as pre-osteoclasts. To increase the stimulatory effects, the particles were composed of PMMA and polyethylene. Under the similar conditions as osteoclast differentiation, we examined the effect of particles on the pro-inflammatory signals in macrophage: the production of TNF-alpha, the activity of MAPKs (mitogen-activated phosphorylation kinase), the expression of I-kappaB (Inhibitory (B) and the production of H2O2 and nitric oxide. RESULTS: The particles stimulated the secretion of TNF-alpha and increased the phosphorylation of p38 and ERK in course of time. The concentration of H2O2 was increased; however the nitric oxide formation was not increased by particle treatment. In addition, the production of H2O2 was synergistically increased by suboptimal stimulation with PMA (phorbol 12-myristate 13-acetate). Expressions of I-kappaB were inhibited by particles. CONCLUSION: The particles may stimulate the activation of MAPKs, the production of TNF-alpha, reactive oxygen species (ROS) and the activation of NF-kappaB in the pre-osteoclasts. We speculate that particles may mediate the pro-inflammatory signal cascade by the activation of NF-kappaB through ROS in pre-osteoclasts, rather than reactive nitrogen species (RNS). Therefore we suggest that the macrophages in inflammatory osteolysis may have the characteristics of pre-osteoclast as well as pro-inflammatory cell. Further researches should be recommended.

Clinical anaysis of failed lumbar disc surgery / 대한정형외과학회잡지

No abstract available.

Surgical treatment of spinal stenosis / 대한정형외과학회잡지

No abstract available.