Rebeca Aguirre-Hernández

Universal foliage‐stem scaling across environments and species in dicot trees: plasticity, biomechanics and Corner’s Rules

Trees range from small-leaved, intricately branched species with slender stems to large-leaved, coarsely branched ones with thick stems. We suggest a mechanism for this pattern, known as Corners Rules, based on universal scaling. We show similar crown area-stem diameter scaling between trunks and branches, environments, and species spanning a wide range of leaf size and stem biomechanics. If crown and stem maintain metabolically driven proportionality, but similar amounts of photosynthates are produced per unit crown area, then the greater leaf spacing in large-leaved species requires lower density stem tissue and, meeting mechanical needs, thicker stems. Congruent with this scenario, we show a negative relationship between leaf size and stem Youngs modulus. Corners Rules emerge from these mutual adjustments, which suggest that adaptive studies cannot consider any of these features independently. The constancy of scaling despite environmental challenges identifies this trait constellation as a crucial axis of plant diversification.

Ontogenetic modulation of branch size, shape, and biomechanics produces diversity across habitats in the Bursera simaruba clade of tropical trees

Organismal size and shape inseparably interact with tissue biomechanical properties. It is therefore essential to understand how size, shape, and biomechanics interact in ontogeny to produce morphological diversity. We estimated within species branch length‐diameter allometries and reconstructed the rates of ontogenetic change along the stem in mechanical properties across the simaruba clade in the tropical tree genus Bursera, measuring 376 segments from 97 branches in nine species in neotropical dry to rain forest. In general, species with stiffer materials had longer, thinner branches, which became stiffer more quickly in ontogeny than their counterparts with more flexible materials. We found a trend from short stature and flexible tissues to tall statures and stiff tissues across an environmental gradient of increasing water availability, likely reflecting a water storage–mechanical support tradeoff. Ontogenetic variation in size, shape, and mechanics results in diversity of habits, for example, rapid length extension, sluggish diameter expansion, and flexible tissues results in a liana, as in Bursera instabilis. Even species of similar habit exhibited notable changes in tissue mechanical properties with increasing size, illustrating the inseparable relationship between organismal proportions and their tissue mechanics in the ontogeny and evolution of morphological diversity.

Plasma Amino Acid Levels Discriminate Between Control Subjects and Mildly Depressed Elderly Women

BACKGROUND AND AIMS Depression is the most common of all psychiatric disorders and the role of amino acid transmitters in this pathology has been recently studied. We undertook this study to investigate if the plasma levels of L-arginine, L-citrulline, L-glutamic acid, L-glutamine, L-asparagine and other amino acids, the L-citrulline/L-arginine and the L-tyrosine/L-phenylalanine ratios, and the nitrite levels are modified in mildly depressed women and if such changes are related to olfactory dysfunction. METHODS Plasma samples were obtained from elderly female subjects (n = 21) with mild depression and (n = 48) controls. Amino acids were analyzed with high-performance liquid chromatography, plasma nitrite levels were measured using the Griess method, and olfactory performance was assessed by the combined testing of odor identification, odor discrimination, odor recognition, and the olfactory threshold. RESULTS Compared to controls, depressed patients had a significantly higher concentration of L-arginine and a significantly lower L-citrulline/L-arginine ratio when the effect of other variables is not taken into account. A logistic regression model allowed us to identify two risk factors for mild depression, L-arginine and L-glutamic acid, and two protective factors, L-asparagine and the L-tyrosine/L-phenylalanine ratio. Additionally, a significant increase in nitrite levels in depressed women was found. No significant differences were found between the percentage of depressed and control women that identified the odors. CONCLUSIONS We identified that the amino acids L-arginine and L-glutamic acid are risk factors for mild depression, whereas L-asparagine and the L-tyrosine/L-phenylalanine ratio are protective factors.

Neuropsychiatric symptoms as risk factors of dementia in a Mexican population: A 10/66 Dementia Research Group study

Cognitive and/or memory impairment are the main clinical markers currently used to identify subjects at risk of developing dementia. This study aimed to explore the relationship between the presence of neuropsychiatric symptoms and dementia incidence.

Adaptation and validation of the Distress Scale for Mexican patients with type 2 diabetes and hypertension: a cross-sectional survey

Objectives The aim of this study was to adapt and validate the Distress Scale for Mexican patients with type 2 diabetes and hypertension (DSDH17M). Setting Two family medicine clinics affiliated with the Mexican Institute of Social Security. Participants 722 patients with type 2 diabetes and/or hypertension (235 patients with diabetes, 233 patients with hypertension and 254 patients with both diseases). Design A cross-sectional survey. Methods The validation procedures included: (1) content validity using a group of experts, (2) construct validity from exploratory factor analysis, (3) internal consistency using Cronbachs α, (4) convergent validity between DSDH17M and anxiety and depression using the Spearman correlation coefficient, (5) discriminative validity through the Wilcoxon rank-sum test and (6) test–retest reliability using intraclass correlation coefficient. Results The DSDH17M has 17 items and three factors explaining 67% of the total variance. Cronbach α ranged from 0.83 to 0.91 among factors. The first factor of ‘Regime-related Distress and Emotional Burden’ moderately correlated with anxiety and depression scores. Discriminative validity revealed that patients with obesity, those with stressful events and those who did not adhere to pharmacological treatment had significantly higher distress scores in all DSDH17M domains. Test–retest intraclass correlation coefficient for DSDH17M ranged from 0.92 to 0.97 among factors. Conclusions DSDH17M is a valid and reliable tool to identify distress of patients with type 2 diabetes and hypertension.

Association of hypertension-related distress with lack of self-care among hypertensive patients.

Abstract Research on factors associated with poor adherence to self-care focuses primarily on psychiatric emotional disorders such as depression and anxiety, whereas non-psychiatric chronic-disease-related emotional distress has received little attention in hypertensive patients. The objective of this study was to evaluate the association of hypertension-related distress with the lack of self-care including low adherence to pharmacological treatment, lack of regular physical activity, low intake of fruits and vegetables and frequent intake of high-salt foods. A cross-sectional survey was conducted in 2014 in two family medical units affiliated with the Mexican Institute of Social Security. The study included 487 hypertensive patients >19 years of age. The conceptual framework for the study was based on the Health Promotion Model. The analysis included multiple Poisson regression models. We found that 21.1% of participants had hypertension-related distress. Low adherence to pharmacological treatment was identified in 45.8% of patients, whereas 46.8% lacked regular physical activity, 30.8% reported a low consumption of fruits and vegetables, and 54.6% frequently consumed foods high in salt content. Hypertension-related distress was associated with lack of regular physical activity and low intake of fruits and vegetables. These findings highlight the importance of addressing distress in order to improve self-care of hypertensive patients.

Prácticas de autoatención en pacientes de los tres niveles de atención en instituciones de salud de México

Objetivo: conocer las practicas de autocuidado en pacientes de unidades hospitalarias de la Secretaria de Salud al inicio de sus padecimientos. Material y metodos: investigacion cualitativa y descriptiva en la cual se eligieron 22 de 57 entrevistas semiestructuradas de una investigacion general sobre satisfaccion de usuarios, en la que los pacientes acudieron a los servicios de consulta externa, hospitalizacion y urgencias. Se utilizaron cuatro de los 120 codigos creados originalmente para conocer las practicas. Resultados: las estrategias empleadas en las practicas de autoatencion, de acuerdo con su importancia, fueron: uso de plantas medicinales, utilizacion de farmacos sin receta, realizacion de actividad fisica, ingesta de alimentos, apoyo espiritual y consumo de drogas. Conclusiones: no obstante que los pacientes fueron atendidos en el tercer nivel de atencion medica, al inicio de su padecimiento utilizaron diversas estrategias encaminadas a su curacion asi como para soportar el dolor y las molestias de la enfermedad.