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1.
Int J Bioprint ; 6(4): 282, 2020.
Article in English | MEDLINE | ID: mdl-33088996

ABSTRACT

Biofabrication is a rapidly evolving field whose main goal is the manufacturing of three-dimensional (3D) cell-laden constructs that closely mimic tissues and organs. Despite recent advances on materials and techniques directed toward the achievement of this goal, several aspects such as tissue vascularization and prolonged cell functionality are limiting bench-to-bedside translation. Extrusion-based 3D bioprinting has been devised as a promising biofabrication technology to overcome these limitations, due to its versatility and wide availability. Here, we report the development of a triple-layered coaxial nozzle for use in the biomanufacturing of vascular networks and vessels. The design of the coaxial nozzle was first optimized toward guaranteeing high cell viability upon extrusion. This was done with the aid of in silico evaluations and their subsequent experimental validation by investigating the bioprinting of an alginate-based bioink. Results confirmed that the values for pressure distribution predicted by in silico experiments resulted in cell viabilities above 70% and further demonstrated the effect of layer thickness and extrusion pressure on cell viability. Our work paves the way for the rational design of multi-layered coaxial extrusion systems to be used in biofabrication approaches to replicate the very complex structures found in native organs and tissues.

2.
Glob Heart ; 13(1): 19-26, 2018 03.
Article in English | MEDLINE | ID: mdl-29146490

ABSTRACT

BACKGROUND: Social determinants differ between countries, which is not always considered when adapting health policies and interventions to face inequalities in noncommunicable diseases and their risk factors. OBJECTIVES: The study sought to analyze educational inequalities in controlled blood pressure (CBP), obesity, and smoking in study populations from Chile and the United States in 2 periods, both countries with large social inequalities. METHODS: The study used data from the first and fifth waves of the MESA (Multiethnic Study of Atherosclerosis) cohort, and the 2003 and 2009 to 2010 Chilean National Health Survey (CNHS) survey outcome measures. The study compared cardiovascular risk factors prevalence as well as relative index of inequality (RII) and slope index of inequality (SII) between the 2 samples. RESULTS: In the CNHS 67.9% and 52.6% of participants had below primary education in 2003 and 2009 to 2010, respectively, compared with 12.3% and 8.1% in the first and fifth waves of the MESA study, respectively. Smoking prevalence was higher and increased in the CNHS compared with the MESA study, concentrated in better-educated women in both years (RII: 0.34; 95% confidence interval [CI]: 0.17 to 0.68; and RII: 0.55; 95% CI: 0.34 to 0.89, respectively). In contrast, smoking decreased over time in the MESA study in all socioeconomic strata, although relative inequalities increased in both sexes (for women, RII: 2.32; 95% CI 1.36 to 3.97; for men, RII: 3.34; 95% CI 2.04 to 5.47). CBP prevalence in both periods was higher in the first and fifth waves of the MESA study (69.7% and 80.2%) compared with the 2003 and 2009 to 2010 CNHS samples (34.2% and 52.3%), but only for the MESA study RII, favoring the better educated, was it significant in both periods and sexes. Obesity inequalities for Chilean women decreased slightly between 2003 and 2009 as prevalence grew in the most educated (RII: 2.21 to 1.68; SII: 0.29 to 0.22, respectively); conversely, they increased for both sexes in the MESA study. CONCLUSIONS: The study findings confirm that patterns and trends in prevalence, and absolute and relative inequalities vary by country, suggesting that context and cultural issues matters.


Subject(s)
Blood Pressure Determination/methods , Blood Pressure/physiology , Cardiovascular Diseases/ethnology , Educational Status , Ethnicity , Patient Education as Topic/standards , Population Surveillance , Aged , Cardiovascular Diseases/prevention & control , Female , Follow-Up Studies , Humans , Male , Prevalence , Risk Assessment/methods , Sex Factors , Socioeconomic Factors , Time Factors , United States/epidemiology
3.
J Clin Hypertens (Greenwich) ; 19(2): 116-125, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27862904

ABSTRACT

The Systolic Blood Pressure Intervention Trial (SPRINT) tested whether a systolic blood pressure (SBP) value <120 mm Hg reduces adverse clinical outcomes compared with the goal of <140 mm Hg. Here the authors describe the baseline characteristics of Hispanic participants in SPRINT. Nondiabetic hypertensive patients 50 years and older with SBP 130-180 mm Hg taking zero to four blood pressure (BP) medications were enrolled from the mainland United States and Puerto Rico. Cross-sectional, bivariate analysis was employed comparing sociodemographic and clinical factors in Hispanics vs non-Hispanics. Multivariable logistic regression models restricted to Hispanics were used to identify factors associated with achieved BP control (SBP <140 mm Hg and diastolic BP <90 mm Hg) at baseline. Eleven percent (n=984) of SPRINT participants were Hispanic; 56% (n=549) of Hispanics were living in Puerto Rico and the remainder were living on the US mainland. Hispanics overall were younger, more often female, less likely to live alone, and more likely to have lower education and be uninsured, although just as likely to be employed compared with non-Hispanics. BP control was not different between Hispanics vs non-Hispanics at baseline. However, a significantly higher percentage of Hispanics on the US mainland (compared with Hispanics in Puerto Rico) had controlled BP. BP control was independently associated with cardiovascular disease history and functional status among Hispanics, specifically those living in Puerto Rico, whereas functional status was the only independent predictor of BP control identified among mainland Hispanics. These findings highlight the diversity of the SPRINT population. It remains to be seen whether factors identified among Hispanics impact intervention goals and subsequent clinical outcomes.


Subject(s)
Antihypertensive Agents/therapeutic use , Blood Pressure/physiology , Hispanic or Latino/statistics & numerical data , Hypertension/drug therapy , Aged , Aged, 80 and over , Blood Pressure/drug effects , Blood Pressure Determination , Cross-Sectional Studies , Female , Humans , Hypertension/physiopathology , Logistic Models , Male , Middle Aged , Puerto Rico , Treatment Outcome , United States/ethnology
5.
Rev. salud pública ; Rev. salud pública;18(2): 300-310, mar.-abr. 2016. ilus, tab
Article in Spanish | LILACS | ID: lil-783670

ABSTRACT

Objetivo Estimar el costo-efectividad de la administración de calcio (1 200 mg diarios) a partir de la semana 14 de gestación a todas las gestantes, comparada con no administrarlo, para reducir la incidencia de preeclampsia. Métodos Se construyó un árbol de decisión en TreeAge® con desenlace en años de vida ganados (AVG). Los costos se incluyeron desde la perspectiva del sistema de salud colombiano, en pesos (COP) de 2014. La tasa de descuento fue de 0%. Se realizaron análisis de sensibilidad univariados y probabilísticos para costos y efectividad. Resultados El suplemento de calcio es una alternativa dominante frente a la no intervención. Si la incidencia de preeclampsia es menor a 51,7 por 1 000 gestantes o el costo por tableta de calcio de 600 mg es mayor a COP$ 507,85, el suplemento de calcio deja de ser una alternativa costo-efectiva en Colombia para un umbral de 3 veces el PIB per cápita de 2013 (COP$ 45 026 379) por AVG. Conclusiones La administración de calcio a todas las gestantes a partir de la semana 14 de gestación es una alternativa dominante frente a la no intervención, que permite ganar 200 años de vida, al tiempo que disminuye costos del orden de COP$ 5 933 millones por 100 000 gestantes.(AU)


Objectives To estimate the cost-effectiveness of administering calcium (1200 mg per day) starting in week 14 of pregnancy to all pregnant women compared to not supplying it to reduce the incidence of preeclampsia. Methods A decision tree was built in TreeAge® with outcome measured in life years gained (LYG) associated with the reduction in maternal deaths. Costs were included from the perspective of the health system in Colombia and expressed in Colombian pesos in 2014 (COP). The discount rate was 0 %. We performed sensitivity univariate and probabilistic analyses for costs and effectiveness. Results Compared to no intervention, calcium supplement is a dominant alternative. If the incidence of preeclampsia is lower than 51.7 per 1 000 pregnant women or the cost per tablet of calcium of 600 mg is greater than COP $507.85, calcium supplement is no longer a cost-effective alternative in Colombia for a threshold of COP $ 45 026 379 (3 times the Colombian per capita GDP of 2013 per LYG). Conclusions Supplying calcium to all pregnant women from week 14 of gestation is a dominant alternative compared to no intervention, which saves 200 LYG, while it decreases costs to the order of COP$5 933 million per 100.000 pregnant women.(AU)


Subject(s)
Humans , Female , Pregnancy , Pre-Eclampsia/mortality , Calcium Carbonate/administration & dosage , Maternal Mortality/trends , Cost-Benefit Analysis , Colombia/epidemiology
6.
Rev Salud Publica (Bogota) ; 18(2): 300-310, 2016 Apr.
Article in Spanish | MEDLINE | ID: mdl-28453041

ABSTRACT

Objectives To estimate the cost-effectiveness of administering calcium (1200 mg per day) starting in week 14 of pregnancy to all pregnant women compared to not supplying it to reduce the incidence of preeclampsia. Methods A decision tree was built in TreeAge® with outcome measured in life years gained (LYG) associated with the reduction in maternal deaths. Costs were included from the perspective of the health system in Colombia and expressed in Colombian pesos in 2014 (COP). The discount rate was 0 %. We performed sensitivity univariate and probabilistic analyses for costs and effectiveness. Results Compared to no intervention, calcium supplement is a dominant alternative. If the incidence of preeclampsia is lower than 51.7 per 1 000 pregnant women or the cost per tablet of calcium of 600 mg is greater than COP $507.85, calcium supplement is no longer a cost-effective alternative in Colombia for a threshold of COP $ 45 026 379 (3 times the Colombian per capita GDP of 2013 per LYG). Conclusions Supplying calcium to all pregnant women from week 14 of gestation is a dominant alternative compared to no intervention, which saves 200 LYG, while it decreases costs to the order of COP$5 933 million per 100.000 pregnant women.


Subject(s)
Calcium Carbonate/economics , Calcium, Dietary/economics , Dietary Supplements/economics , Pre-Eclampsia/mortality , Pre-Eclampsia/prevention & control , Calcium Carbonate/administration & dosage , Calcium, Dietary/administration & dosage , Colombia , Cost-Benefit Analysis , Decision Trees , Female , Humans , Maternal Mortality , Pregnancy , Pregnancy Trimester, Second
7.
J Am Heart Assoc ; 4(7)2015 Jun 24.
Article in English | MEDLINE | ID: mdl-26109505

ABSTRACT

BACKGROUND: We assessed high cholesterol (HC) awareness, treatment, and control rates among US Hispanic/Latino adults and describe factors associated with HC awareness and management. METHODS AND RESULTS: Baseline data (collected 2008-2011) from a multisite probability sample of Hispanic/Latino adults in the Hispanic Community Health Study/Study of Latinos (18 to 74 years old; N=16 207) were analyzed. HC was defined as low-density lipoprotein-cholesterol ≥130 mg/dL and/or total cholesterol ≥240 mg/dL or use of cholesterol-lowering medication. Among Hispanic/Latino adults with HC, almost half (49.3%) were not aware of their condition and only 29.5% were receiving treatment. Men had a higher HC prevalence than women (44.0% versus 40.5%) but a lower rate of treatment (28.1% versus 30.6%). Younger adults were significantly less likely to be HC aware compared to those who were older. Those with hypertension, diabetes, and high socioeconomic position were more likely to be HC aware. US-born Hispanic/Latino were more likely to be HC unaware than foreign-born Hispanics/Latinos, but longer US residency was significantly associated with being HC aware, treated, and controlled. Cholesterol control was achieved among 64.3% of those who were HC treated. However, younger adults, women, those with lower income, those uninsured, and more recent immigrants were less likely to be HC controlled. Individuals of Puerto Rican or Dominican background were most likely to be HC aware and treated, whereas those of Mexican or Central American background were least likely to be HC treated. Individuals of Cuban and South American background had the lowest rates of HC control, whereas Puerto Ricans had the highest. CONCLUSIONS: Understanding gaps in HC awareness, treatment, and control among US Hispanic/Latino adults can help inform physicians and policymakers to improve disease management and patient education programs.


Subject(s)
Anticholesteremic Agents/therapeutic use , Awareness , Cholesterol/blood , Health Knowledge, Attitudes, Practice/ethnology , Hispanic or Latino/psychology , Hypercholesterolemia/drug therapy , Hypercholesterolemia/ethnology , Adolescent , Adult , Age Factors , Aged , Biomarkers/blood , Comorbidity , Cuba/ethnology , Female , Health Status Disparities , Healthcare Disparities/ethnology , Humans , Hypercholesterolemia/blood , Hypercholesterolemia/diagnosis , Hypercholesterolemia/psychology , Male , Middle Aged , Patient Education as Topic , Prevalence , Puerto Rico/ethnology , Risk Factors , Sex Factors , South America/ethnology , Time Factors , Treatment Outcome , United States/epidemiology , Up-Regulation , Young Adult
8.
PLoS One ; 10(4): e0124517, 2015.
Article in English | MEDLINE | ID: mdl-25906072

ABSTRACT

OBJECTIVE: We sought to determine the contribution of psychological variables to risk for metabolic syndrome (MetS) among Latinos enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA), and to investigate whether social support moderates these associations, and whether inflammatory markers mediate the association between psychological variables and MetS. RESEARCH DESIGN AND METHODS: Cross-sectional analyses at study baseline were conducted with a national Latino cohort (n = 1,388) that included Mexican Americans, Dominican Americans, Puerto Rican Americans and Central/South Americans. Hierarchical logistic regression analyses were conducted to test the effects of psychosocial variables (chronic stress, depressive symptoms, and social support) on MetS. In addition, separate subgroup-specific models, controlling for nationality, age, gender, socioeconomic position, language spoken at home, exercise, smoking and drinking status, and testing for the effects of chronic stress, depressive symptoms and inflammation (IL-6, CRP, fibrinogen) in predicting risk for MetS were conducted. RESULTS: In the overall sample, high chronic stress independently predicted risk for MetS, however this association was found to be significant only in Mexican Americans and Puerto Rican Americans. Social support did not moderate the associations between chronic stress and MetS for any group. Chronic stress was not associated with inflammatory markers in either the overall sample or in each group. CONCLUSIONS: Our results suggest a differential contribution of chronic stress to the prevalence of MetS by national groups.


Subject(s)
Hispanic or Latino/psychology , Metabolic Syndrome/psychology , Aged , C-Reactive Protein/analysis , Cross-Sectional Studies , Female , Humans , Interleukin-6/analysis , Logistic Models , Male , Metabolic Syndrome/ethnology , Metabolic Syndrome/pathology , Middle Aged , Odds Ratio , Risk Factors , Socioeconomic Factors
9.
Am J Med ; 127(12): 1186-94.e1, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25195188

ABSTRACT

BACKGROUND: The prevalence and determinants of dyslipidemia patterns among Hispanics/Latinos are not well known. METHODS: Lipid and lipoprotein data were used from the Hispanic Community Health Study/Study of Latinos­a population-based cohort of 16,415 US Hispanic/Latinos ages 18-74 years. National Cholesterol Education Program cutoffs were employed. Differences in demographics, lifestyle factors, and biological and acculturation characteristics were compared among those with and without dyslipidemia. RESULTS: Mean age was 41.1 years, and 47.9% were male. The overall prevalence of any dyslipidemia was 65.0%. The prevalence of elevated low-density lipoprotein cholesterol was 36.0%, and highest among Cubans (44.5%; P < .001). Low high-density lipoprotein cholesterol (HDL-C) was present in 41.4% and did not significantly differ across Hispanic background groups (P = .09). High triglycerides were seen in 14.8% of Hispanics/Latinos, most commonly among Central Americans (18.3%; P < .001). Elevated non-HDL-C was seen in 34.7%, with the highest prevalence among Cubans (43.3%; P < .001). Dominicans consistently had a lower prevalence of most types of dyslipidemia. In multivariate analyses, the presence of any dyslipidemia was associated with increasing age, body mass index, and low physical activity. Older age, female sex, diabetes, low physical activity, and alcohol use were associated with specific dyslipidemia types. Spanish-language preference and lower educational status were associated with higher dyslipidemia prevalence. CONCLUSION: Dyslipidemia is highly prevalent among US Hispanics/Latinos; Cubans seem particularly at risk. Determinants of dyslipidemia varied across Hispanic backgrounds, with socioeconomic status and acculturation having a significant effect on dyslipidemia prevalence. This information can help guide public health measures to prevent disparities among the US Hispanic/Latino population.


Subject(s)
Acculturation , Hispanic or Latino/statistics & numerical data , Hypercholesterolemia/ethnology , Hypertriglyceridemia/ethnology , Motor Activity , Adolescent , Adult , Age Factors , Aged , Alcohol Drinking/ethnology , Central America/ethnology , Cholesterol, HDL/blood , Cholesterol, LDL/blood , Comorbidity , Cuba/ethnology , Diabetes Mellitus/ethnology , Dominican Republic/ethnology , Dyslipidemias/ethnology , Educational Status , Female , Humans , Hypercholesterolemia/blood , Hypertriglyceridemia/blood , Male , Middle Aged , Overweight/ethnology , Prevalence , Sex Factors , Statistics as Topic , Triglycerides/blood , United States/epidemiology , Young Adult
10.
Acta Odontol Latinoam ; 26(2): 90-6, 2013.
Article in English | MEDLINE | ID: mdl-24303732

ABSTRACT

Nickel-Titanium rotary files are a technological development that enables dentists to prepare irregularly shaped root canals without altering them. Unfortunately, these files may fracture without any prior visible warning signs. The aim of this study was to perform a theoretical evaluation of the mechanical behaviour of Mtwo Nickel-Titanium rotary files for endodontics, in order to determine which of the files in the basic series are most likely to fracture. Mathematical models of the Mtwo basic file series were analyzed using the finite elements method. Bending and torsion loads were applied to the files both under normal conditions and under extreme conditions, to determine which of them had the highest Von Mises stresses. When the approximation was similar to normal use none of the file models reached the maximum limit of failure by fracture. When used inadequately, file models 10/0.04 and 25/0.06 had the highest Von Mises stresses for bending and torsion, respectively. Thus, it is recommended that Mtwo files 10/0.04 and 25/0.06 should be used once only, to prevent fractures.


Subject(s)
Dental Instruments , Materials Testing , Nickel , Titanium , Finite Element Analysis
11.
Am J Hypertens ; 26(5): 673-82, 2013 May.
Article in English | MEDLINE | ID: mdl-23547037

ABSTRACT

BACKGROUND: Little information is available about the relationship of socioeconomic status (SES) to blunted nocturnal ambulatory blood pressure (ABP) dipping among Hispanics and whether this relationship differs by race. We sought to characterize ABP nondipping and its determinants in a sample of Hispanics. METHODS: We enrolled 180 Hispanic participants not on antihypertensive medications. SES was defined by years of educational attainment. All participants underwent 24-hour ABP monitoring. A decrease of <10% in the ratio between average awake and average asleep systolic BP was considered nondipping. RESULTS: The mean age of the cohort was 67.1 ± 8.7, mean educational level was 9.4 ± 4.4 years, and 58.9% of the cohort was female. The cohort was comprised of 78.3% Caribbean Hispanics with the rest from Mexico and Central/South America; 41.4% self-identified as white Hispanic, 34.4% self-identified as black Hispanic, and 24.4% did not racially self- identify. The percentage of nondippers was 57.8%. Educational attainment (10.5 years vs. 8.6 years; P <0.01) was significantly higher among dippers than nondippers. In multivariable analyses, each 1-year increase in education was associated with a 9% reduction in the likelihood of being a nondipper (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.84-0.98; P = 0.01). There were significantly greater odds of being a nondipper for black Hispanics than for white Hispanics (OR, 2.83, 95% CI, 1.29-6.23; P = 0.005). Higher SES was significantly protective of nondipping in white Hispanics but not black Hispanics. CONCLUSIONS: These results document a substantial prevalence of nondipping in a cohort of predominantly normotensive Hispanics. Dipping status varied significantly by race. Lower SES is significantly associated with nondipping status, and race potentially impacts on this relation.


Subject(s)
Blood Pressure/physiology , Circadian Rhythm/physiology , Hispanic or Latino , Psychology , Racial Groups , Social Class , Aged , Black People , Blood Pressure Monitoring, Ambulatory , Caribbean Region , Central America , Cohort Studies , Educational Status , Female , Humans , Male , Mexico , Middle Aged , South America , White People
13.
Acta odontol. latinoam ; Acta odontol. latinoam;26(2): 90-96, 2013. tab, graf
Article in English | LILACS | ID: lil-723410

ABSTRACT

Las limas rotatorias de níquel-titanio son un avance tecnológico que permite al odontólogo llevar a cabo tratamientos en conductos con morfologías irregulares Lamentablemente, estos instrumentos pueden fracturarse sin presentar señales visibles que permitan prevenir este accidente. Por lo tantoel objetivo del presente estudio fue evaluar teóricamente el comportamientomecánico de las limas rotatorias de Níquel-Titanio para uso en endodoncia Mtwo® para determinar cuál de losinstrumentos de la serie básica es el que presenta mayor probabilidad de fractura. Con este fin se realizó un análisis por medio del método de los elementos finitos utilizando modelos matemáticos de los instrumentos de la serie básica de las limas Mtwo®. Aestos instrumentos se les aplicaron cargas de flexión y torsión en condiciones normales y en condiciones extremas, para determinar cuáles presentaban los esfuerzos de Von Mises más altos. En una aproximación similar al uso normal, ninguno de los modelosde las limas alcanzó el limite máximo de falla por fractura. Ante un uso inadecuado, los modelos de las limas 10/0.04 y 25/0.06 mostraron los esfuerzos de Von Mises más altos tanto a flexión como a torsión respectivamente, por lo tanto se recomienda dar un solo uso a la lima 10/0.04 y a la lima 25/0.06 de Mtwo® para prevenir la fractura de estos instrumentos.


Nickel-Titanium rotary files are a technological development thatenables dentists to prepare irregularly shaped root canals withoutaltering them. Unfortunately, these files may fracture without anyprior visible warning signs. The aim of this study was to perform atheoretical evaluation of the mechanical behaviour of Mtwo®Nick-el-Titanium rotary files for endodontics, in order to determinewhich of the files in the basic series are most likely to fracture.Mathematical models of the Mtwo®basic file series were analyzedusing the finite elements method. Bending and torsion loads wereapplied to the files both under normal conditions and under extremeconditions, to determine which of them had the highest Von Misesstresses. When the approximation was similar to normal use, noneof the file models reached the maximum limit of failure by fracture.When used inadequately, file models 10/0.04 and 25/0.06 had thehighest Von Mises stresses for bending and torsion, respectively.Thus, it is recommended that Mtwo®files10/0.04 and 25/0.06should be used once only, to prevent fractures.


Subject(s)
Dental High-Speed Equipment , Dental Instruments , Nickel , Root Canal Preparation/instrumentation , Titanium , Dental Alloys , Materials Testing
14.
Acta odontol. latinoam ; Acta odontol. latinoam;26(2): 90-6, 2013.
Article in Spanish | BINACIS | ID: bin-132808

ABSTRACT

Nickel-Titanium rotary files are a technological development that enables dentists to prepare irregularly shaped root canals without altering them. Unfortunately, these files may fracture without any prior visible warning signs. The aim of this study was to perform a theoretical evaluation of the mechanical behaviour of Mtwo Nickel-Titanium rotary files for endodontics, in order to determine which of the files in the basic series are most likely to fracture. Mathematical models of the Mtwo basic file series were analyzed using the finite elements method. Bending and torsion loads were applied to the files both under normal conditions and under extreme conditions, to determine which of them had the highest Von Mises stresses. When the approximation was similar to normal use none of the file models reached the maximum limit of failure by fracture. When used inadequately, file models 10/0.04 and 25/0.06 had the highest Von Mises stresses for bending and torsion, respectively. Thus, it is recommended that Mtwo files 10/0.04 and 25/0.06 should be used once only, to prevent fractures.


Subject(s)
Dental Instruments , Materials Testing , Nickel , Titanium , Finite Element Analysis
15.
Acta odontol. latinoam ; Acta odontol. latinoam;26(2): 90-96, 2013. ^gtab, graf
Article in English | BINACIS | ID: bin-129974

ABSTRACT

Las limas rotatorias de níquel-titanio son un avance tecnológico que permite al odontólogo llevar a cabo tratamientos en conductos con morfologías irregulares Lamentablemente, estos instrumentos pueden fracturarse sin presentar señales visibles que permitan prevenir este accidente. Por lo tantoel objetivo del presente estudio fue evaluar teóricamente el comportamientomecánico de las limas rotatorias de Níquel-Titanio para uso en endodoncia Mtwo« para determinar cuál de losinstrumentos de la serie básica es el que presenta mayor probabilidad de fractura. Con este fin se realizó un análisis por medio del método de los elementos finitos utilizando modelos matemáticos de los instrumentos de la serie básica de las limas Mtwo«. Aestos instrumentos se les aplicaron cargas de flexión y torsión en condiciones normales y en condiciones extremas, para determinar cuáles presentaban los esfuerzos de Von Mises más altos. En una aproximación similar al uso normal, ninguno de los modelosde las limas alcanzó el limite máximo de falla por fractura. Ante un uso inadecuado, los modelos de las limas 10/0.04 y 25/0.06 mostraron los esfuerzos de Von Mises más altos tanto a flexión como a torsión respectivamente, por lo tanto se recomienda dar un solo uso a la lima 10/0.04 y a la lima 25/0.06 de Mtwo« para prevenir la fractura de estos instrumentos.(AU)


Nickel-Titanium rotary files are a technological development thatenables dentists to prepare irregularly shaped root canals withoutaltering them. Unfortunately, these files may fracture without anyprior visible warning signs. The aim of this study was to perform atheoretical evaluation of the mechanical behaviour of Mtwo«Nick-el-Titanium rotary files for endodontics, in order to determinewhich of the files in the basic series are most likely to fracture.Mathematical models of the Mtwo«basic file series were analyzedusing the finite elements method. Bending and torsion loads wereapplied to the files both under normal conditions and under extremeconditions, to determine which of them had the highest Von Misesstresses. When the approximation was similar to normal use, noneof the file models reached the maximum limit of failure by fracture.When used inadequately, file models 10/0.04 and 25/0.06 had thehighest Von Mises stresses for bending and torsion, respectively.Thus, it is recommended that Mtwo«files10/0.04 and 25/0.06should be used once only, to prevent fractures.(AU)


Subject(s)
Dental Instruments , Nickel , Titanium , Root Canal Preparation/instrumentation , Dental High-Speed Equipment , Materials Testing , Dental Alloys
16.
Rev. costarric. cienc. méd ; 13(3/4): 7-13, set.-dic. 1992.
Article in Spanish | LILACS | ID: lil-130273

ABSTRACT

Se analiza las características clínicas, radiológicas, espirométricas y gasimétricas de 11 pacientes que estuvieron internadas en el Servicio de Medicina Interna de Hospital de La Anexión, Guanacaste, Costa Rica, en diferentes momentos de un período total de nueve meses, en el año 1990. Las pacientes tenían el antecedente común de una prolongada exposición al humo de leña (más de 30 años). Se encontró en ellas la asociación de este antecedente común de una prolongada exposición al humo de leña (más de 30 años). Se encontró en ellas la asociación de este antecedente con la presencia de una neumopatía caracterizada clínicamente por tos, expectoración mucosa y disnea. Funcionalmente en la espirometría se encontró una mayor alteración del FEF25-75 por ciento, sin una disminución significativa del índice FEV1/CV. Los estudios gasimétricos demostraron una elevación global de la gradiente alveolo-arterial de oxígeno y la radiología estuvo caracterizada por la presencia de un infiltrado intersticial bilateral de predominio basal.


Subject(s)
Humans , Female , Adult , Middle Aged , Lung Diseases/etiology , Smoke , Costa Rica
18.
Acta méd. costarric ; 31(2): 47-50, mayo 1988.
Article in Spanish | LILACS | ID: lil-81089

ABSTRACT

Entre los meses de enero 1980 y diciembre de 1987,se efectuaron 138 biopsias pleurales cerradas, en el Hospital Mexico de la CCSS, las cuales correspondieron a 123 pacientes estudiados en las salas de medicina y de neumologia. Trienta y tres biopsias fueron reportadas como infiltracion por neoplasia(24%); treinta como pleuritis cronica granulomatosa compatible con tuberculosis(21.7%); setenta y cinco biopsias tuvieron diagnosticos no especificos(54.3%)tales como pleuritis cronica,pleuritis aguda y cronica,fibrosis pleural,necrosispleural,pleuritis fibrinosa, no diagnostico y pleura sin lesiones. En este grupode diagnosticos no especificos, mediante otros estudios se logro demostrar que una tercera parte de ellos correspondian a neoplasias(32%)y un 7% adicional a tuberculosis pleural, lo cual ilustra la importancia de repetir el procedimiento y/o insistir en otros recursos de gran rendimiento como son la citologia de liquido pleural y los cultivos de las muestras de biopsia, en aquellos casos en los que se sustenta fuertemente patologia pleural, a pesar de un primer estudio negativo o con resultado inespecifico. Considerando los diagnosticos finales en todos los casos, obtenidos procedimientos clinicos,quirurgicos o por autopsia, el rendimiento global de la biopsia pleural fue de 60% en neoplasia y de 80% en tuberculosis. En nuestro medio, de todos los derrames pleurales exudativos estudiados,un 73% (neoplasia 45%,tuberculosis 28%) corresponden con patologia pleural, pulmonar o sistematica severa.


Subject(s)
Humans , Biopsy, Needle/pathology , Lung Diseases/diagnosis , Costa Rica
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