46 research outputs found

    Contribución al estudio del modelado matemático de la fermentación sólida de hongos filamentosos en soportes inertes

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    In the solid state fermentation (SSF) field, inert supports are ideal experimental media in whxh specific culture media can be absorbed. In these ideal media, the microorganisms use the water and nutrients contained inside the support and colonize available surfaces producing commercial metabolites. Inert supports in a regular shape presentation are also particularly interesting as an ideal media in developing mathematical models. In ths work a mathematical model dealing with the growth of filamentous fungi on a packed bed of regular spherical shape inert support is developed, solved, and verified. To develop the model, a local phenomenological approach for a system constituted by a porous heterogeneous medium or inert support containing water and nutrients is considered. Cell growth takes place on the surface of porous medium and microorganisms exchange mass with liquid phase, within the support, and with the surrounding continuos gaseous phase. The general model deals with six state-variables: (i) biomass, (ii) sugar, (iii) water, (iv) oxygen, (iv) carbon dioxide, and (v) medium temperature; a set of hypotheses was taken account. The dynamic and spatial behavior of each state variable is derived from correspondent kinetics and mass and energy balances. The proposed general model involves: (i) six partial differential equations, six initial, and five boundary conditions, (ii) 13 kinetic and balances associated algebraic equations, and (iii) 43 parameters including physical and biological constants and the particular operation conditions. In order to solve such a general model, two complexity levels were approached: 1. In the first level, the general model was simplified to an only time-dependent model. This simplification reduced the model to (i) six ordinary differential equation and six initial conditions, (ii) 13 algebraic equations, and (iii) 36 parameters. All parameters were estimated as a function of the physical characteristics of each constituent, the particular operation conditions, and a stoichiometrical reaction which transforms sugars into biomass. The model, in a cylindrd coordinate system, and in a normalized form was solved by using the fourth order Runge-Kutta numerical integration algorithm. 2. 'In the second level, the general model was retained as time and space-dependent. In this level, same values for parameters found in the simplified model were used and for the rest of parameters new values were searched. The model, in a cylindrical coordinate system, and in a normalized form was solved by using the finite differences method, in which an explicit in time, explicit in the axial ordinate, and implicit in the radial ordinate strategy was used. Qualitative and quantitative results, in all of the two approaches, showed a good agreement with the physical and biological principles that encouraged the model. To validate and fit results the simplified model was used. Model predictions were compared to experimental results obtained under different operation conditions (increasing initial sugar concentrations were also included) by using small packed bed reactors at laboratory scale. It was found that sugar consumption and cell growth were clearly influenced by the following parameters (i) the biomass yields (Yi), (ii) the maintenance coefficient (m,), (iii) the affinity substrate cefficient (&), and (iv) the inhibition constant (K,). It was shown that these biological parameters could not be considered as a constants but variables as a function of fermentation time, Le. as a function of any state variable such as sugar in the medium. In order to fit experimental satisfactorily, it was shown that should be necessary to include different values for the kinetic parameters to fit cell growth and different values to fit sugar consumption, particularly in the cases of K, and q. Therefore, when trying to fit results always a multiple solutions problem was emerged. To solve such a problem the yields Yi, were explicited as a function of sugar in the medium. The introduction of the Yi function in the model allowed to keep constant values for the rest of biological parameters producing satisfactory fittings. In order to justify simulated cell growth patterns with, sugar and oxygen consumption, carbon dioxide, and metabolic heat evolution, it was shown, practically in all assayed cases in whch high initial sugar concentration was used, that a product formation term is required in the model. The proposed simplified model can be regarded as a flexible quick-response simulator with an acceptable accuracy to experimental data. Furthermore, the model could be a helpful simulation tool in: (i) explaining physical and physiological aspects involved in the studied phenomenon, (ii) developing the suitable bioreactor operating strategies for any other SSF culture, (iii) Setting up bases to the design, control and scale-up of bioreactors, and (iv) developing more complex models such as diffusive models.En el campo de las fermentaciones en medios sólidos (FMS), los soportes inertes se utilizan como medios experimentales ideales en los que se absorben medios de cultivo especificos. En estos medios ideales, los microorganismos utilizan el agua y los nutrientes que contiene el soporte y colonizan las superficies disponibles para producir metabolitos de interés comercial. La utilización de soportes inertes de forma regular también resulta interesante como un medio ideal para la elaboración de modelos matemáticos. En este trabajo, se desarrolló la formulación, solución y validación de un modelo matemático que: describe el crecimiento de un hongo filamentoso sobre el lecho empacado de un soporte inerte de forma esférica regular. Para la formulación del modelo, se utilizó un enfoque fenomenológico local en un sistema constituido por un medio poroso heterogéneo o soporte inerte que contiene agua y nutrientes en su interior. En la superficie de este medio poroso los microorganismos crdcen intercambiando materia con la fase líquida del interior del soporte y, con la fase gaseosa continua que los rodea. Con base en un conjunto de hipótesis, se desarrolló un modelo general constituido por seis variables de estado: (i) biomasa, (ii) azúcares solubles, (iii) agua, (iv) oxígeno, (v) bióxido de carbono, y (vi) temperatura del medio. El comportamiento de cada variable de estado, en el tiempo y en el espacio, se obtiene a partir de los balances de masa, los balances de energía interna y las relaciones cinéticas correspondientes. El modelo general quedó constituido por: (i) seis ecuaciones diferenciales parciales, seis condiciones iniciales y cinco condiciones frontera, (ii) 13 ecuaciones algebraicas asociadas a los balances y las relaciones cinéticas y, (iii) 43 parámetros que incluyen constantes fisicas, biológicas y las condiciones de operación particulares. de sustrato son los siguientes: (i) los rendimientos base producción de biomasa (Yi), (ii) el coeficiente de mantenimiento (m,), (iii) el coeficiente de afinidad por el sustrato (&) y, (iv) el coeficiente de mhbición por el sustrato (IC,). Se demostró que estos parámetros biológicos, no podían considerarse constantes y que debían cambiar con el tiempo de fermentación, i.e. con respe,cto a alguna variable de estado como los azúcares en el medio. También se demostró que, para ajustar satisfactoriamente los resultados experimentales, sería necesario incorporar diferentes valores en los parámetros cinkticos, tanto para el caso del crecimiento, como para el consumo de los azúcares, particularmente los parámetros K, y m,. Por lo tanto, al tratar de ajustar los resultados del modelo, se encontró que el problema tenía múltiples soluciones. Para resolver este problema se utilizó una función que permitió asociar los rendimientos de biomasa Yi con los azúcares del medio. Esta función permitió emplear valores constantes de los tres parámetros IC,, aC, y m, con ajustes satisfactorios a los resultados experimentales. Prácticamente en todos los casos en los que se trató de validar el modelo con altas concentraciones iniciales de azúcares se observó, que se requiere incluir en el modelo al menos un término de formación de producto que justifique el crecimiento celular con el consumo de azúcares, el consumo de oxígeno, y la producción de bióxido de carbono y calor metabólico. El modelo simplificado que se propone, es un simulador flexible de rápida respuesta, con un aceptable grado de fidelidad con los resultados experimentales. Es un modelo que puede contribuir: (i) a la explicación de aspectos físicos y fisiológicos del fenómeno global estudiado, (ii) al desarrollo de las estrategias de operación de biorreactores para otros cultivos en FMS. (iii) a establecer bases para el diseño, control y escalamiento de biorreactores y, (iv) al desarrollo de nuevos modelos más complejos, como es el caso de modelos que consideren los aspectos difusivos de los nutrientes y de los productos

    Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

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    Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

    Contributions of mean and shape of blood pressure distribution to worldwide trends and variations in raised blood pressure: A pooled analysis of 1018 population-based measurement studies with 88.6 million participants

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    © The Author(s) 2018. Background: Change in the prevalence of raised blood pressure could be due to both shifts in the entire distribution of blood pressure (representing the combined effects of public health interventions and secular trends) and changes in its high-blood-pressure tail (representing successful clinical interventions to control blood pressure in the hypertensive population). Our aim was to quantify the contributions of these two phenomena to the worldwide trends in the prevalence of raised blood pressure. Methods: We pooled 1018 population-based studies with blood pressure measurements on 88.6 million participants from 1985 to 2016. We first calculated mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP) and prevalence of raised blood pressure by sex and 10-year age group from 20-29 years to 70-79 years in each study, taking into account complex survey design and survey sample weights, where relevant. We used a linear mixed effect model to quantify the association between (probittransformed) prevalence of raised blood pressure and age-group- and sex-specific mean blood pressure. We calculated the contributions of change in mean SBP and DBP, and of change in the prevalence-mean association, to the change in prevalence of raised blood pressure. Results: In 2005-16, at the same level of population mean SBP and DBP, men and women in South Asia and in Central Asia, the Middle East and North Africa would have the highest prevalence of raised blood pressure, and men and women in the highincome Asia Pacific and high-income Western regions would have the lowest. In most region-sex-age groups where the prevalence of raised blood pressure declined, one half or more of the decline was due to the decline in mean blood pressure. Where prevalence of raised blood pressure has increased, the change was entirely driven by increasing mean blood pressure, offset partly by the change in the prevalence-mean association. Conclusions: Change in mean blood pressure is the main driver of the worldwide change in the prevalence of raised blood pressure, but change in the high-blood-pressure tail of the distribution has also contributed to the change in prevalence, especially in older age groups

    A century of trends in adult human height

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    Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants.

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    BACKGROUND: Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. METHODS: We used data from 1990 to 2019 on people aged 30-79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. FINDINGS: The number of people aged 30-79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306-359) million women and 317 (292-344) million men in 1990 to 626 (584-668) million women and 652 (604-698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55-62) of women and 49% (46-52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43-51) of women and 38% (35-41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20-27) for women and 18% (16-21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. INTERPRETATION: Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings. FUNDING: WHO

    Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

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    Background Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. Methods We used data from 1990 to 2019 on people aged 30-79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. Findings The number of people aged 30-79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306-359) million women and 317 (292-344) million men in 1990 to 626 (584-668) million women and 652 (604-698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55-62) of women and 49% (46-52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43-51) of women and 38% (35-41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20-27) for women and 18% (16-21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. Interpretation Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings. Copyright (C) 2021 World Health Organization; licensee Elsevier

    Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

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    Background Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. Methods We used data from 1990 to 2019 on people aged 30–79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. Findings The number of people aged 30–79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306–359) million women and 317 (292–344) million men in 1990 to 626 (584–668) million women and 652 (604–698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55–62) of women and 49% (46–52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43–51) of women and 38% (35–41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20–27) for women and 18% (16–21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. Interpretation Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings

    Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

    Get PDF
    Background Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. Methods We used data from 1990 to 2019 on people aged 30–79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. Findings The number of people aged 30–79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306–359) million women and 317 (292–344) million men in 1990 to 626 (584–668) million women and 652 (604–698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55–62) of women and 49% (46–52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43–51) of women and 38% (35–41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20–27) for women and 18% (16–21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. Interpretation Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings
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