Abstract Introduction. In 2021, the Secretaría de Salud de México and the Pan American Health Organization launched an initiative to interrupt intra-domiciliary vector transmission of Trypanosoma cruzi based on the prevalence of Chagas disease in children. The Mexican State of Veracruz was leading this initiative. Objective. To estimate the seroprevalence of T. cruzi infection among children under 15 years of age from rural areas of Veracruz, México. Materials and methods. We identified eight localities of high priority from the Municipality of Tempoal, Veracruz, for baseline serology. Blood samples were collected on filter paper from 817 individuals between June and August 2017, for screening with a third-generation enzyme immunoassay. Reactive cases were confirmed by indirect hemagglutination, enzyme-linked immunosorbent assay, and indirect immunofluorescence tests on peripheral blood serum samples. We calculated seroprevalence and 95% confidence intervals (CI). Results. We confirmed Chagas disease cases in children under 15 years of age with a seroprevalence of 1,9% (95 % CI = 1,12-3,16) in the localities of Citlaltepetl, Cornizuelo, Cruz de Palma and Rancho Nuevo. Conclusions. These results indicate recent transmission of T. cruzi in these communities and allow to establish an epidemiological baseline for the design and implementation of a model focused on geographical areas with active transmission to advance toward the elimination of intra-domiciliary vector transmission of this parasite in Mexico.

Resumen Introducción. En el 2021, la Secretaría de Salud de México y la Organización Panamericana de la Salud lanzaron una iniciativa para interrumpir la transmisión vectorial intradomiciliaria de Trypanosoma cruzi, fundamentada en la prevalencia de la enfermedad de Chagas en la población infantil. El estado mexicano de Veracruz fue el pionero de esta iniciativa. Objetivo. Estimar la seroprevalencia de infección por T. cruzi en menores de 15 años de localidades rurales de Veracruz, México. Materiales y métodos. Se identificaron ocho localidades prioritarias para la serología basal del municipio de Tempoal, Veracruz. Entre junio y agosto de 2017, se recolectaron muestras de sangre en papel filtro de 817 individuos para su tamizaje mediante un inmunoensayo enzimático de tercera generación. Los casos reactivos del tamizaje se confirmaron mediante pruebas de hemaglutinación indirecta, ensayo de inmunoabsorción ligado a enzimas e inmunofluorescencia indirecta en muestras de suero. Se calculó la seroprevalencia y su intervalo de confianza (IC) del 95 %. Resultados. En las localidades de Citlaltépetl, Cornizuelo, Cruz de Palma y Rancho Nuevo se confirmaron casos de la enfermedad de Chagas en menores de 15 años con una seroprevalencia de 1,9 % (IC 95 % = 1,12-3,16). Conclusiones. Los resultados indican que estas comunidades presentan transmisión reciente de T. cruzi y permiten establecer una línea epidemiológica de base para el diseño e implementación de un modelo dirigido a aquellas áreas geográficas con transmisión activa. Se espera que dicho modelo contribuya a la eliminación de la transmisión vectorial intradomiciliaria del tripanosomátido en México.

Resumen La alimentación durante los primeros 1000 días de vida (desde el vientre materno hasta los dos años) son fundamentales para la salud futura de una persona. Este artículo tiene por objetivo analizar los saberes y prácticas alimentarias materno-infantiles en localidades rurales del Estado de Hidalgo en México. Estudio de corte transversal, descriptivo, observacional desde una perspectiva fenomenológica combinando técnicas cuantitativas y cualitativas en 56 participantes y 7 informantes a quienes se entrevistó. El 48% de las mujeres entrevistadas ofrecieron leche materna exclusivamente durante 4 a 6 meses, el 57% destetó después del año. La familia fue la principal fuente de información de las mujeres (91%), por encima del personal de salud (80%), quien frecuentemente da opiniones contradictorias. El 71% prefirió el uso de conocimientos de herbolaria provenientes de parteras, hijas de parteras o adultas mayores. Los saberes, tradiciones y prácticas alimentarias de las madres de menores de dos años en el Carso Huasteco hidalguense, se basan en conocimientos tradicionales permeados por el discurso del personal de salud y los medios de comunicación, así como el acceso físico y económico a los alimentos procesados y frescos.

Abstract Nutrition during the first 1000 days of life (from the womb to two years of age) is fundamental for the future health of a person. The objective of this article is to analyze maternal and child feeding knowledge and practices in rural localities of the state of Hidalgo in Mexico. A cross-sectional, descriptive, observational study was carried out from a phenomenological perspective combining quantitative and qualitative techniques in 56 participants and 7 informants who were interviewed. 48% of the women interviewed offered breast milk exclusively for 4 to 6 months, 57% weaned after one year. The family was the main source of information for the women (91%), above the health personnel (80%), who frequently gave contradictory opinions. Seventy-one percent preferred the use of herbal knowledge from midwives, daughters of midwives, or older women. The knowledge, traditions, and food practices of mothers of children under two years of age in the Carso Huasteco hidalguense are based on traditional knowledge permeated by the discourse of health personnel and the media, as well as physical and economic access to processed and fresh foods.

ABSTRACT This study investigated the knowledge and perception of Brazilian pig producers in terms of environmental enrichment (EE) for pigs, the materials used, and the forms of presentation, identifying the single conditions that can improve their application on pig farms. A questionnaire was applied to 1340 farms – representing 7.4% of the farms and 12% of the sows in the country. The questions included descriptions of farms and respondents, their knowledge, judgments and level of interest in the use of EE, and frequency of use of the materials. Enrichment was used in 89.1% of farms, but half of the respondents admitted to using it without knowing what was involved. The producers presented an optimistic view (92.3%) about the application of this tool and were interested in receiving more knowledge and guidance on the subject (97.8%). The materials were used mainly to avoid fights (46.3%) and to prevent tail biting (23.3%); on the other hand, the increase in production costs (39.6%) and lack of knowledge about the subject (31.3%) were the main reasons for not using enrichment; concerns about increased management on farms were sporadic (7.1%). Metal chains were the main artifacts used, followed by plastic containers and pieces of wood; the same breeding farm used up to five types of materials. The fact that the respondents stated that they knew what EE was and that they had a good perspective on its use were significant conditions for the use of some kind of enrichment on the farms. Younger farm owners were more likely to use enrichment materials than more experienced ones. The results suggested that Brazilian pig producers use EE even with limited knowledge about the subject and that there is an argument to improve the use of this animal welfare strategy.

Resumen Introducción. El trauma es reconocido como una epidemia global que varía según las regiones donde se presenta. Una parte de la carga de la enfermedad está determinada por los años perdidos de vida potencial, la cual es una estimación de amplio uso para la vigilancia en salud pública; sin embargo, existe poca información disponible en relación a esto. El objetivo de este estudio fue determinar la tendencia de los años perdidos de vida potencial por el trauma en un período de nueve años. Métodos. La información se obtuvo del Instituto Nacional de Medicina Legal y Ciencias Forenses en un período de nueve años (2007-2015). La población de referencia se determinó con base en las proyecciones del Departamento Administrativo Nacional de Estadística, que indicaron una expectativa de vida de 75 años. Resultados. En el 2015, a las lesiones por traumatismos en Colombia les correspondieron 1.920,7 años perdidos de vida potencial por cada 100.000 personas. Durante el período de estudio, las principales causas fueron los homicidios (rango, 51 a 68 %) y los accidentes de tránsito (rango, 19 a 28 %); la relación entre hombres y mujeres fue de 7:1, y la tendencia estadística fue hacia la disminución de los años perdidos de vida potencial. Conclusiones. Los homicidios siguen aportando el mayor número de lesiones por trauma y años perdidos de vida potencial. Los hombres jóvenes continuaron siendo la población mayormente afectada. Se conceptúa la necesidad de incrementar los esfuerzos para mejorar la vigilancia en salud pública y ahondar en las intervenciones oportunas relacionadas con el trauma.

Abstract Introduction: Trauma is a worldwide leading cause of external injuries that varies according to the regions. In 2015, trauma injuries were the third cause of Disability Adjusted Life Years (DALYs) with the 9% of the total global burden of disease. A portion of the burden of disease is determined by the Years of Potential Life Lost (YPLL). In Colombia in 2015, from the total of deaths due to external cause injuries, homicides had the highest number of YPLL with a total of 495.667; traffic accidents had 236.237 YPLL and accidental deaths 90.745 YPLL. The YPLL trauma trends and baselines are important to public health surveillance but there’s no consolidated description. The aim of this study is to determine trauma trends in a five-year period. Material and methods: The information was obtained from the reports of Instituto Nacional de Medicinal Legal y Ciencias Forenses in a nine-year period (2007-2015). The reference population was identified through the population projections from the Departmento Administrativo Nacional de Estadistica (DANE). YPLL calculation was compared to a 75 years life expectancy. Results: In 2015 trauma injuries in Colombia had a total of 1.920,7 YPLL per 100.000 people. Overall the study period, leading cause of YPLL was homicides (range= 51-68%) and traffic accidents (range= 19-28%), ratio male: female was 7:1 and YPLL observed had decreased. The percentage of the total decrease was 6.3%, the highest increase was observed in 2009 with a raise of 30.5%. Conclusions: Homicides are a major public health issue such as the leading cause in YPLL of trauma injuries. Despite there was no increase in sex ratio, younger males are getting more affected trough the time increasing YPLL in this population group. More efforts are needed to improve public health surveillance for assessing baselines, DALYs, policies and evidence for interventions in trauma-related injuries.

RESUMO Objetivo: avaliar a eficácia da estratégia adotada e a qualidade do atendimento em trauma pediátrico na sobrevivência dos pacientes atendidos após desastre em uma cidade do interior de Minas Gerais, em comparação a resultados esperados por estudos sobre mortalidade infantil em grandes queimados. Métodos: análise retrospectiva observacional de dez pacientes que sofreram queimaduras e foram transferidos para um centro de referência de trauma. Utilizou-se o escore de R-Baux modificado para estimar a mortalidade esperada. Comparou-se a mortalidade esperada a partir do escore de R-Baux e a mortalidade real, a partir do teste de uma proporção. Comparou-se, também, tempo de admissão pós-trauma com mortalidade e grau de superfície corporal queimada com mortalidade. Resultados: o R-Baux médio foi de 75,2, o que significa uma mortalidade esperada para grandes queimados de 5%. No entanto, a mortalidade do grupo com grande área de superfície corporal queimada desse estudo foi de 60%, valor p=0,001. Observou-se neste caso uma mortalidade muito além da esperada pela literatura. Conclusão: apesar das inúmeras variáveis, aventa-se a hipótese de infraestrutura de atendimento em trauma pediátrico aquém da necessária no Estado. Este estudo sugere maior incentivo à políticas públicas para atendimento de trauma pediátrico, centro de referência preparado, acordos de transferência bem estabelecidos e otimização de planos de catástrofe para diminuição da morbimortalidade para os pacientes que sobrevivem à primeira hora após o trauma.

ABSTRACT Objective: to evaluate the effectiveness of the adopted strategy and the care quality for pediatric trauma in the survival of patients attended after a disaster in a city in the interior of Minas Gerais state, compared to the expected results of studies on infant mortality in major burns. Methods: retrospective observational analysis of ten patients who were burned and transferred to a trauma reference center. We used the modified R-Baux score to estimate the expected mortality. We compared the expected mortality predicted by R-Baux score and the actual mortality determined from one-ratio test. We also compared time of post-trauma admission with mortality and burned body surface area with mortality. Results: mean R-Baux score was 75.2, which means an expected mortality of 5% among major burn patients. However, in this study, mortality in the group of children with large burned body surface area was of 60%, p=0.001, a rate far beyond that expected in literature. Conclusion: despite the innumerable variables, we consider the hypothesis of the pediatric trauma care infrastructure being inferior than the one needed in the state. This study suggests a greater incentive for public policies concerning pediatric trauma care, prepared referral center, well-established transfer agreements, and optimization of catastrophe plans, in order to reduce morbimortality of patients who survive the first hour after trauma.

RESUMO Objetivo: analisar a associação de mortalidade com variáveis sociodemográficas, clínicas, lesões e complicações em pacientes com trauma de pelve decorrente de trauma contuso. Métodos: estudo retrospectivo e observacional com dados de registro de trauma obtidos durante cinco anos. O óbito foi a variável de estratificação das análises. Para verificar se as variáveis de interesse tinham associação com o óbito, foi realizado o teste t de Student e teste do Qui-quadrado (ou Fisher) e Wilcoxon-Mann Whitney. Os fatores independentemente associados ao óbito foram analisados por modelo logístico binomial, e com base nos testes de Wald e por Critérios de Informação de Akaike (AIC) e Bayesiano de Schwarz (BIC). Resultados: dos 28 pacientes com fratura de pelve por trauma contuso, 23 (82,1%) eram homens; 16 (57,1%) com média de idade de 38,8 anos (desvio padrão 17,3). Houve 98 lesões ou fraturas nos 28 pacientes. Quanto à gravidade, sete pacientes tiveram Injury Severity Score superior a 24 (25%). O tempo de internação hospitalar médio foi 26,8 dias (DP=22,4). Quinze pacientes (53,6%) tiveram internação em UTI. A incidência de óbito foi de 21,4%. A análise mostrou que idade igual ou maior do que 50 anos e presença de coagulopatia foram fatores independentemente associados ao óbito. Conclusão: as fraturas de pelve podem ter mortalidade elevada. Neste estudo a mortalidade foi superior ao que é descrito na literatura. A idade acima de 50 anos e a coagulopatia se revelaram fatores de risco nessa população.

ABSTRACT Objective: to analyze the association of mortality with sociodemographic and clinical variables, as well as lesions and complication in patients with pelvic trauma due to blunt trauma. Methods: we conducted a retrospective, observational study with five-year trauma record data. Death was considered as the main stratification variable for the analyzes. We used the Student t test to compare means, the Chi-Square or Fisher exact test for proportions, and the Wilcoxon-Mann Whitney test for medians. We analyzed the independent factors using a logistic regression model with penalized likelihood, based on the Wald tests, the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). Results: of the 28 patients with blunt trauma fracture, 23 (82.1%) were men; 16 (57.1%) were, in average, 38.8 years old (±17.3). There were 98 lesions or fractures in the 28 patients. As for severity, seven people had Injury Severity Score higher than 24 (25%). The mean hospital stay was 26.8 days (±22.4). Fifteen patients (53.6%) had ICU admission. Mortality was 21.4%. The analysis showed that age 50 years or more and presence of coagulopathy were factors independently associated with death. Conclusion: pelvic fractures can have high mortality. In this study, mortality was higher than that described in the literature. Age above 50 years and the presence of coagulopathy are risk factors in this population.

The duration of Untreated Psychosis (DUP), defined as the period of time between the onset of psychotic symptoms, such as hallucinations and delusions, and the first effective treatment, has been associated to prognosis of schizophrenia. It has been demonstrated that although psychotic symptoms are initially detected by relatives of patients with schizophrenia, they take a long time to seek specialized attention, which in turn leads to a delay in the diagnosis and treatment of the disorder. Schizophrenia has been considered by the World Health Organization as a public health problem and has been placed as the ninth cause of incapacity in the world. Thus, DUP represents part of this public health problem. In Mexico, the average DUP lasts 64 weeks, which is very similar to the average observed in other countries, where the mean DUP in psychotic patients varies between one and two years. One of the main reasons of a prolonged DUP is that patients and their families first assist with a general practitioner which, in many cases, does not perform an adequate diagnosis with the subsequent referral to a psychiatric facility, and the treatment given for the patient is based on sedative medication. This is also Mexico's case, where seeking help primarily involves religious groups, with very few referrals to psychiatric facilities and with inadequate treatment support, which delays care in specialized services. It has been established that early treatment is related to a better prognosis and outcome, while treatment delay has been related to a longer time to achieve symptom remission. These results support the hypothesis that the presence of psychotic symptoms for a long period of time may predispose to biological damage, which may in turn lead to predominant negative symptoms and severe cognitive deficits after the first psychotic episode. Also, some studies have found that a longer DUP is related to a more insidious illness onset, frequent relapses and psychiatric hospitalizations during the course of the disorder, with a poor response to antipsychotic medication. Through the use of neuroimaging, several studies have found the relation between DUP and brain morphology in patients with schizophrenia. Studies using Magnetic Resonance Imaging (MRI) have reported that patients with longer DUP show a significant reduction in the gray matter of the temporal planum, in the left middle, inferior temporal, left occipital and left fusiform cortices, with an increase of grey matter in the left basal ganglia, and a volume reduction of the caudate nucleus. These results may be related to the clinical course of the disorder in terms of a higher symptom severity and poor treatment response. In regard to psychosocial variables related to DUP, it has been observed that men have a longer DUP when compared to women and patients that are single and unemployed also have a longer DUP. Consequently, it has been found that there is a relationship between DUP and premorbid adjustment in patients with schizophrenia. Premorbid adjustment is defined as the psychosocial functioning in the educational, occupational, social and interpersonal relations areas before the evidence of positive characteristic symptomatology, where symptoms are not secondary to an organic cause and cover a period of six months before the first psychiatric hospitalization or contact with a psychiatric facility. In addition, it has been found that a prolonged DUP is related to a poor premorbid adjustment, especially during late adolescence and adulthood. This association may suggest the presence of prodromic symptoms secondary to the physiopathological process of psychosis. Consequently, if a patient shows some of the initial symptoms of the disorder, including psychosocial impairment, his/her abilities to be aware of the symptoms may be limited to seek for medical care, which may in turn increase DUP. Furthermore, some authors have reported that some variables related to the patient's environment are related with DUP. The main variable pointed out is: the previous experience with mental disorders and psychiatric facilities. Patients whose families had previous experience of a mentally ill relative, report a shorter DUP when compared to families with no previous history of an ill relative. Also, it has been analised that patients with an adequate social network have a shorter DUP compared to those patients whose social network is inadequate or limited. Based on these results, some authors have proposed two phenotypes for psychotic disorders: the first one characterized by males, poor premorbid adjustment, long DUP, insidious onset of the disorder and a stable pattern of negative symptoms. The second phenotype was one characterized by the following variables: females, good premorbid adjustment, a shorter DUP, acute illness onset and absence of a stable pattern of negative symptoms. This definition may be useful to determine the course of the disorder in patients with schizophrenia and may be able to predict the clinical outcome. Thus, DUP can be used as an indicator of prognosis in patients with schizophrenia and its evaluation should be promoted. Although these two phenotypes are very useful, caution should be warranted in their use to avoid generalization. By and large, the studies related to the clinical impact of DUP emphasized the need to reduce DUP through early detection programs, including psychoeducation. We believe that this approach will be useful to identify individuals at an early development of a psychotic illness so that interventions can begin before symptoms have reached a level of significant impairment for the patient and warranting referrals by the family, school or health providers. Based on the studies reviewed above, we can conclude that DUP has a definitive impact on the prognosis of patients with schizophrenia and that future studies should be performed including it not only as a predictor of clinical outcome, but also as an specific clinical target for mental health research. Increasing the knowledge about the relationship between DUP and clinical course of schizophrenia is crucial to create and promote early detection and intervention programs such as the ones that have started all over the world, where the main objective is to identify young people who are at risk of developing psychotic disorders, specially schizophrenia.

La duración de la psicosis no tratada (DPNT), definida como el período de tiempo entre la aparición de los síntomas psicóticos y el inicio de un tratamiento adecuado, está asociada al pronóstico de la esquizofrenia, enfermedad que ha sido considerada por la Organización Mundial de la Salud, como un problema de salud pública. El atraso en la búsqueda de tratamiento especializado conlleva a un retraso en el diagnóstico y tratamiento adecuados de la enfermedad. En México, el promedio de la DPNT es de 64 semanas, siendo éste similar al reportado en otros países, donde la media varía entre uno y dos años. Se ha comprobado que el retraso en el tratamiento adecuado del padecimiento está relacionado con un pobre pronóstico, lo cual apoya la hipótesis de que la presencia de síntomas psicóticos durante un largo período de tiempo puede predisponer a un daño biológico, generando así un predominio de síntomas negativos y mayores déficit cognitivos después del primer episodio psicótico. Además, se ha encontrado que una DPNT larga se relaciona con un inicio insidioso de la enfermedad, mayor número de recaídas y rehospitalizaciones psiquiátricas durante el curso de la enfermedad, además de una pobre respuesta al tratamiento farmacológico con antipsicóticos. En cuanto a las variables demográficas y psicosociales que se asocian con una DPNT prolongada encontramos: al sexo masculino, el no tener pareja u ocupación laboral. Asimismo, se ha reportado que los pacientes que presentan un mayor deterioro en su funcionamiento premórbido, son aquellos que muestran una mayor DPNT. Esta asociación sugiere que los pacientes con esquizofrenia pueden presentar síntomas prodrómicos mucho tiempo antes de que su funcionamiento se vea totalmente afectado por el proceso fisiopatológico de la psicosis. Asimismo, se han reportado variables relacionadas con el entorno del paciente asociadas a la DPNT. Entre ellas, destacan la experiencia previa con trastornos mentales y las redes sociales. Se ha observado que los pacientes de familias que han tenido una experiencia previa con otro familiar diagnosticado con alguna enfermedad mental, muestran una menor DPNT en contraste con aquellos cuyas familias no han tenido experiencias previas de enfermedades mentales. De igual forma, se ha informado que pacientes con una adecuada red social tienen una menor DPNT, comparados con aquellos cuya red social es limitada. A partir de estos hallazgos se han propuesto dos fenotipos para los trastornos psicóticos cuya definición puede ser útil para determinar el curso clínico de la enfermedad en pacientes con esquizofrenia. En este sentido, la DPNT se puede utilizar como un indicador para el pronóstico de pacientes con esquizofrenia, por lo que se sugiere promover su evaluación. Los estudios que se han llevado a cabo sobre el impacto clínico de la DPNT enfatizan la necesidad de reducirla mediante programas de detección temprana. Estos programas serían útiles para identificar personas en etapas iniciales de un trastorno psicótico y se podría realizar una intervención profesional antes de que los síntomas alcancen un nivel de deterioro significativo para el paciente. Con base en lo anterior, se puede concluir que la DPNT tiene un fuerte impacto sobre el pronóstico de los pacientes con esquizofrenia y que en el futuro se deben realizar estudios que la incluyan no sólo como un factor pronóstico, sino como un objetivo clínico específico de la investigación en salud mental, ya que la información que se genere puede ser la base para la creación y promoción de programas de detección e intervención tempranas.

Several extracts of aerial parts of Leonotis nepetaefolia showed anti-inflammatory activity on TPA-induced edema model. The chromatography of the extracts led to the isolation of stigmasterol and leonotinin. Although the presence of leonotinin is in agreement with previous phytochemical studies of this species, this is the first time that its anti-inflammatory activity is determined.

Diversos extractos de las partes aéreas de Leonotis nepetaefolia mostraron poseer propiedades antiinflamatorias en el modelo de edema inducido por TPA en oreja de ratón. La cromatografía de los extractos permitió el aislamiento de estigmasterol y leonotinina. La presencia de leonotinina está de acuerdo con estudios previos de esta especie. Sin embargo, es la primera ocasión que se informa la actividad antiinflamatoria de este compuesto.

Introduction: Nowadays commercial companies offer many possibilities to select abutments for implant-supported prostheses. With this work we want to show the selection criteria according to the type of the prosthesis, localization and direction of the implants, as well as to the existing alternatives. Materials and Method: We have used a bibliographic review and our own experiences obtained from our activities to point out the abutments indicated and their alternatives. Results: For the fixed maxillary rehabilitation we prefere conic abutments for cemented pros-thesis. If the implants are not well orientated, we shall use conic abutments for screwed restorations. In the mandible we indicate conic abutments for screwed hybrid prostheses. In overdentures we select conic abutments to screw a retention bar as a first option. In partial cases we prefere, as in single replacements, conic abutment to cement; if the direction is inadequate we use metallic or ceramic abutments. We indicate in the article the reasons and alternatives in each situation.

Introducción: hoy día las casas comerciales ofrecen muchas posibilidades a la hora de seleccionar los pilares para nuestras prótesis implantosoportadas, lo que hace a veces difícil su selección. Con este trabajo queremos mostrar los criterios para escogerlos según el tipo de prótesis, su localización, la dirección de los implantes y las alternativas existentes. Materiales y Método: se ha empleado una revisión bibliográfica y experiencias propias de nuestra actividad para señalar los pilares indicados y sus posibles alternativas. Resultados: para la rehabilitación fija maxilar superior preferimos pilares cónicos tallables para prótesis cementada. Si los implantes no están paralelos usaremos pilares cónicos para atornillar para confeccionar una prótesis híbrida. En la mandíbula indicamos pilares cónicos para atornillar. En las sobredentaduras seleccionamos pilares cónicos para atornillar una barra de retención como primera opción. En los casos parciales preferimos pilares cónicos para cementar, así como en los unitarios. Si la dirección es desfavorable usaremos pilares metálicos o cerámicos tallables. Señalamos en el artículo las razones y alternativas en cada situación.