Selection and interpretationof soil quality indicators for forest recovery after clearing of a tropical montane cloud forest in Mexico

Through slash-and-burn techniques, vast areas formerly occupied by tropical montane cloud forest (TMCF) in Mexico have been converted into croplands and secondary forest of different ages. Despite the dramatic changes in soil properties and processes detected during cropping and forest regeneration, no attempts have been made to develop soil quality indicators (SQI) to assist in the assessment of soil conditions during such changes. SQI are considered to be essential in evaluating plans of forest restoration or management; as such, the objectives of this study were to (i) select soil properties that can be used as SQI during forest regeneration for abandoned crop fields in a TMCF area managed under the slash-andburn method; and (ii) examine the ecological significance of stand age for function-based interpretations of the selected SQI. To this end, the soil properties of three adjacent chronosequences in El Rincón, Sierra Norte, Southern Mexico were analyzed. Each chronosequence consisted of ordered series of five stands of different age after abandonment: a cornfield and adjacent forests of 15 (incipient forest), 45 (young forest), 75 (mature forest), andP100 (old-growth forest) years after abandonment. The soil properties of undisturbed old-growth forest stands were used as a reference. After inspection of principal component analysis results and control charts, the following soil properties were chosen as SQI in TMCF areas: soil organic carbon, pH, plant-available P, O horizon thickness and exchangeable Al3+. The selected SQI displayed different rates of change during forest regeneration. Soil organic carbon had a fast recovery rate and, therefore, a greater ability to return to its original level after disturbance. In contrast, O horizon thickness, soil pH, plant-available P, and exchangeable Al3+ showed a slow rate of change during the fallow period. SQI did not always change linearly nor improve with the age of the forest. The highest exchangeable Al3+ concentration was detected in 45-year-old forests, suggesting that at this forest age, soil become an important filter against Al3+ sensitive species, potentially affecting vegetation composition. Considering the slow recovery rate of some SQI, we estimate that fallow periods of at least 100 years are required in order to reach good soil quality in TMCF ecosystems. Management practices should therefore consider the maintenance of forest of different ages spanning at least 100 years in the landscape. Doing so would achieve more sustainable management practices by allowing a relatively continuous recovery of the ecosystem without prolonged interruptions of land utilization

Antioxidant Role of Vitamin E in Atherogenesis Induced by Hyperfibrinogenemia

We used an experimental model of atherogenesis to evaluate the effect of vitamin E on oxidative stress induced by hyperfibrinogenemia (HF) and the possible normalization of oxidative stress markers. The following variables were studied: nitric oxide (NO), L-citrulline, superoxide dismutase (SOD) activity and regression of histopathological lesions in the thoracic aorta. The study was performed in 36 Wistar rats that were divided into three groups of 12 rats each: A, control group; B, HF for 90 days; C, HF for 90 days + vitamin E. Hyperfibrinogenemia was induced by the injection of epinephrine (0.1 ml/day/rat) during 90 days. The dose of vitamin E was 2 mg/day/rat during 75 days. We measured the plasma levels of fibrinogen (mg/dl), NO (uM) and L-citrulline (mM); SOD activity (U/ml) was assayed in red cell lysates using spectrophotometry. The histopathological sections of the thoracic aorta were examined using light microscopy (LM). Statistical analysis was performed using MANOVA and Fisher’s test; a p value <0.05 was considered statistically significant. Rats in group B had a significant increase in fibrinogen levels B (407±8.9 mg/dl) compared to groups A (203±9 mg/dl) and C (191.58±17.79 mg/dl) (p<0.001). We observed a significant decrease in NO in group B (13.73±1.76 uM) versus groups A (23.58±0.08 uM) and C (26.64±3.65 uM) (p<0.001). L-citrulline increased significantly in groups B (4.99±0.18 mM) and C (6.60±0.16 mM) compared to group A (3.03±0.13 mM) (p<0.001). SOD activity was greater in groups B (251.67±10.34 U/ml) and C (304.75±10.43 U/ml) versus group A (139.44±4.74 U/ml) (p<0.001). Light microscopic examination revealed the presence of endothelial denudation, intimal thickening and vessel wall protrusion in group B (90%), while recovery of endothelial denudation and a 50% reduction in intimal thickening was observed in group C (p<0.001). High SOD activity might be insufficient to prevent abnormalities in the oxidative stress pathway induced by HF. Vitamin E would stop the chain reaction initiated by free radicals and thus decrease the superoxide anion, stimulating the bioavailability of NO with normalization of fibrinogen plasma levels.Con el propósito de estudiar el efecto de la vitamina E sobre el estrés oxidativo desencade- nado por hiperfibrinogenemia (HF) en un modelo experimental de aterogénesis y la posible normalización de los indicadores de estrés oxidativo, se evaluaron: óxido nítrico (NO), L-citrulina, superóxido dismutasa (SOD) e involución de lesiones histopatológicas en la aorta torácica. El estudio se realizó en 36 ratas, cepa Wistar, que se dividieron en tres grupos (n = 12 cada uno): A, control; B, HF × 90 días; C, HF × 90 días + vitamina E. La HF se indujo mediante inyecciones de adrenalina (0,1 ml/día/rata) por 90 días. La dosis de vitamina E fue de 2 mg/día/rata durante 75 días. Se dosaron en plasma los niveles de fibrinógeno (mg/dl), NO (uM) y L-citrulina (mM) y en lisado de glóbulos rojos, por espectrofotometría, se determinó la actividad de la SOD (U/ml). Se analizaron cortes de la aorta torácica por microscopia óptica (MO). Rev Argent Cardiol 2010;78:405-410

Myelo peroxidase as an Indicator of Oxidative Stress in Metabolic Syndrome

Background: Increased myeloperoxidase (MPO) activity would be the link between the rise of the inflammatory response and oxidative stress (OS) in metabolic syndrome (MS). Objective: The aim of this study was to determine the enzymatic activity of MPO associated with OS in animals with MS and establish their relationship with probable cardiovascular injury. Methods: Male Wistar rats were divided into two groups: Group A, control (n=12) and Group B, induced MS (n=12). Metabolic syndrome was produced by 6-week administration of 10% fructose diluted in the drinking water. Insulin (mU/ml), glucose (mg/dl), lipid panel (mg/dl), HOMA (homeostatic model assessment), MPO (IU/ml) and superoxide dismutase (SOD) activity (U/ml) were measured. Light microscopy was used for the histological study of the heart and thoracic aorta. Results: Group B showed significantly increased levels of plasma glucose (176±17.3 mg/dl), insulin (29.5±4.52 mU/ml), HOMA (11±1.3), total cholesterol (133±9.6 mg/dl) and triglycerides (75±12.9 mg/dl) compared with Group A: plasma glucose (115±1.1 mg/dl), insulin (4±0.82 mU/ml), HOMA (3±0.38), total cholesterol (69.7±1.6 mg/dl) and triglycerides (46.2±6 mg/dl), (p<0.001 for all variables). A significant decrease in HDL (28.3±1.14 mg/dl) in Group B vs. Group A (61±1.0 mg/dl) (p<0.001) validated the experimental MS model. Myeloperoxidase activity increased significantly in Group B (181.3±15.7 IU/ml) vs. Group A (116.07±4.2 IU/ml) (p<0.001). A similar behavior was seen with SOD antioxidant activity in Group B (181±6 U/ml) vs. Group A (138±3.6 U/ml) (p <0.01). Light microscopy of the heart and thoracic aorta revealed histopathological changes in animals with induced MS. Conclusion: Increased MPO and SOD in Group B would indicate the presence of OS in MS, with consequences at the vascular level.Introducción: Los incrementos en la actividad de la mieloperoxidasa (MPO) serían el nexo entre el aumento de la respuesta inflamatoria y el estrés oxidativo (EO) en el síndrome metabólico (SM). Objetivo: Determinar la actividad de la enzima MPO asociada con EO en animales con SM y establecer su relación con las probables lesiones cardiovasculares. Material y métodos: Se utilizaron ratas macho de la cepa Wistar, que se dividieron en: Grupo A, control (n = 12) y Grupo B, inducción de SM (n = 12). El SM se indujo con la administración de fructosa al 10% diluida en agua de bebida durante 6 semanas. Se cuantificaron insulina (mU/ml), glucemia (mg/dl), perfil lipídico (mg/dl), HOMA (homeostatic model assessment), MPO (UI/ml) y actividad de la superóxido dismutasa (SOD) (U/ml). Se estudió la histología de la aorta torácica y el corazón por microscopia óptica. Resultados: Se observaron niveles de glucemia (176 ± 17,3 mg/dl), insulina (29,5 ± 4,52 mU/ml), HOMA (11 ± 1,3), colesterol total (133 ± 9,6 mg/dl) y triglicéridos (75 ± 12,9 mg/dl) incrementados significativamente en el Grupo B en comparación con el Grupo A: glucemia (115 ± 1,1 mg/dl), insulina (4 ± 0,82 mU/ml), HOMA (3 ± 0,38), colesterol total (69,7 ± 1,6 mg/dl) y triglicéridos (46,2 ± 6 mg/dl) (p < 0,001 para todas las variables); se verificó disminución significativa de los valores de HDL (28,3 ± 1,14 mg/dl) en el Grupo B en comparación con el Grupo A (61 ± 1,01 mg/dl) (p < 0,001), validando así el modelo experimental de SM. La actividad de la MPO se incrementó significativamente en el Grupo B (181,3 ± 15,7 UI/ml) respecto del Grupo A (116,07 ± 4,2 UI/ml) (p < 0,001). Similar comportamiento presentó la actividad antioxidante de la SOD en el Grupo B (181 ± 6 U/ml) respecto del Grupo A (138 ± 3,6 U/ml) (p < 0,01). Las microscopias ópticas de corazón y de aorta torácica evidenciaron cambios histopatológicos en los animales con SM inducido. Conclusión: Los incrementos de la MPO y la SOD en el Grupo B demostrarían la presencia de EO, con repercusión a nivel vascular en el SM

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P &lt; 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)