Estimación de la edad de Swietenia macrophylla (Meliaceae) a partir del diámetro normal en poblaciones del sureste mexicano

Introducción: Swietenia macrophylla King ("caoba") es la especie arbórea de mayor importancia comercial en el sureste mexicano y utilizada como guía en el manejo forestal, por lo que conocer su edad y tasas de crecimiento es fundamental para la sostenibilidad de los aprovechamientos maderables. Objetivos: Estimar laedad (E t ) a partir del método del 'tiempo de paso' (Tp) y calcular las tasas de crecimiento absoluto (TCA) y relativo (TCR) para Swietenia macrophylla en Quintana Roo, México. Métodos: Se ajustaron ecuaciones para calcular TCA y TCR con remediciones periódicas durante 15 años del diámetro normal (d) en 403 árboles de S. macrophylla en Felipe Carrillo Puerto, Quintana Roo, México; también, se determinaron el Tp y la E t para el cálculo del incremento corriente anual (ICA) e incremento medio anual (IMA), y definir así los turnos comercial y técnico. Resultados: La máxima TCR se alcanzó a los 28 cm de d (0.015 cm año-1) (aplicación de aclareos), mientras que la mayor TCA (0.69 cm año-1) y menor Tp (3.5 años) a los 55 cm de d (turno comercial). El máximo ICA al considerar la E t fue de 1.43 cm en la categoría diamétrica de 50 cm, con un IMA de 0.67 cm año-1 a una edad de 75 años, mientras que el turno técnico (ICA = IMA) se alcanzó a los 96 años (incrementos de 0.78 cm año-1). Conclusiones: A través de mediciones periódicas del diámetro normal en S. macrophylla es posible obtener su edad, además los resultados pueden ser utilizados para elaborar programas de manejo y ejecutar prácticas silvícolas que propicien el incremento diamétrico en Quintana Roo.

Introduction: Swietenia macrophylla King (Mahogany) is the most commercially important tree species in Southeastern of Mexico and is used as a guide in forest management. Therefore, knowing its age and growth rates is essential for the sustainability of timber harvest. Objective: Estimate the age (Et) from the 'step time' (Tp) method and calculate the absolute (TCA) and relative (TCR) growth rates for Swietenia macrophylla in Quintana Roo, Mexico. Methods: Equations were adjusted to calculate TCA and TCR with periodic re-measured for 15 years of the normal diameter (d) in 403 S. macrophylla trees in Felipe Carrillo Puerto, Quintana Roo, Mexico. Tp and Et were determined for the calculation of the annual current increase (ICA) and average annual increase (IMA), to define the commercial and technical shifts. Results: The maximum TCR was reached at 28 cm of d (0.015 cm year-1) (thinning application), whereas the highest TCA (0.69 cm year-1) and lower Tp (3.5 years) at 55 cm of d (commercial shift). The maximum ICA when considering Et was 1.43 cm in the 50 cm of diametric category with an IMA of 0.67 cm year-1 at an age of 75 years, while the technical shift (ICA = IMA) was reached at 96 years (increments of 0.78 cm year-1). Conclusions: Through periodic measurements of the normal diameter in S. macrophylla it is possible to obtain its age, these results also can be used to elaborate management programs and apply silvicultural practices that propitiate the diametric increase in Quintana Roo.

Risk factors associated with cardiovascular morbidity and mortality in Spanish incident hemodialysis patients: two-year results from the ANSWER study.

AIMS: To identify factors associated with cardiovascular (CV) disease in hemodialysis. METHODS: Multicenter, prospective, 2-year, observational study in 2,310 incident patients (3,496 patient-years). Multivariate Cox models determined baseline characteristics associated with CV disease. RESULTS: Main factors associated with CV deaths (6.3/100 patient-years) were: high Charlson score (hazard ratio (HR) 3.6; 95% confidence interval (CI) 1.7-7.5 for ≥9 vs. ≤4); low Karnofsky score (KS; HR 2.2; 95% CI 1.5-3.3 for KS ≤50 vs. >70); female gender (HR 1.4; 95% CI 1.1-1.9); catheter access (HR 1.4; 95% CI 1.0-1.9); low (<3.5 g/dl) albumin (HR 2.5; 95% CI 1.8-3.3); ferritin deficiency (HR 1.6; 95% CI 1.2-2.2 for <100 vs. ≥100-500 ng/ml) and low body mass index (BMI; HR 1.9; 95% CI 1.2-3.0 for <20 vs. 20-25). A BMI of ≥30 was a protective factor (HR 0.6; 95% CI 0.4-0.9). CONCLUSIONS: There is a high CV risk, especially in older patients with high comorbidity, low BMI, low albumin or iron deficiency. Catheter access increases the CV death risk.

Mortality in incident haemodialysis patients: time-dependent haemoglobin levels and erythropoiesis-stimulating agent dose are independent predictive factors in the ANSWER study.

BACKGROUND: Although the association between low haemoglobin levels and mortality is well established in haemodialysis patients, data are conflicting regarding levels >12 g/dl. In addition, divergent results have been reported on the relation between erythropoiesis-stimulating agents (ESAs) and mortality. METHODS: This was a multicentre, observational, prospective, 24-month study, which recruited Spanish incident haemodialysis patients (N = 2310). Univariate and multivariate time-dependent Cox regression models examined the longitudinal association of mortality with haemoglobin and ESA dose; adjustment was made for iron deficiency and other confounders. RESULTS: After adjusting for age, functional status, body mass index, albumin levels, catheter as vascular access, previous history of cardiovascular disease, neoplasia, and ESA dose, mortality decreased with increasing haemoglobin. Adjusted hazard ratios relative to the reference category (11-12 g/dl) and 95% confidence intervals were: 1.36 (1.01-1.86) for 13 g/dl. Independent of haemoglobin, patients on sustained ESA doses of 1-4000 IU/week and 8001-16 000 IU/week had better survival than non-treated (reference) patients, with adjusted hazard ratios of 0.61 (0.41-0.90) and 0.68 (0.49-0.94), respectively. No significant difference was found for doses of 4001-8000 IU/week or >16,000 IU/week, adjusted hazard ratios of 0.87 (0.63-1.20) and 0.89 (0.63-1.28), respectively. CONCLUSIONS: Higher haemoglobin levels are associated with lower mortality in Spanish incident haemodialysis patients, regardless of ESA dose, comorbidity, vascular access or malnutrition. No increase in mortality occurs for high ESA doses, independent of haemoglobin levels.

Baseline characteristics of an incident haemodialysis population in Spain: results from ANSWER--a multicentre, prospective, observational cohort study.

BACKGROUND: The ANSWER study aims to identify risk factors leading to increased cardiovascular morbidity and mortality in a Spanish incident haemodialysis population. This paper summarizes the baseline characteristics of this population. METHODS: A prospective, observational, one-cohort study, including all consecutive incident haemodialysis patients from 147 Spanish nephrology services, was conducted. Patients were enrolled between October 2003 and September 2004. Sociodemographic, clinical, laboratory and health care characteristics were collected. RESULTS: Baseline characteristics are described for 2341 incident haemodialysis patients [mean (SD) age 65.2 (14.5) years, 63% males]. The main cause of renal failure was diabetic nephropathy (26%). The majority of patients (57%) had a Karnofsky score of 80-100 and 27% were followed up by a nephrologist for 500 ng/ml, 41% and saturated transferrin <20 or >40%, 50%) despite previous treatment with erythropoiesis-stimulating agents in 41% of cases. CONCLUSIONS: There is excessive use of temporary catheters and a high prevalence of uraemia-related cardiovascular risk factors among incident haemodialysis patients in Spain. The poor control of hypertension, anaemia, malnutrition and mineral metabolism and late referral to a nephrologist indicate the need for improving the therapeutic management of patients before the onset of haemodialysis.

Conversion from calcineurin inhibitors to sirolimus in chronic allograft dysfunction: changes in glomerular haemodynamics and proteinuria.

BACKGROUND: The study was conducted in order to describe possible intraglomerular haemodynamic changes inducing proteinuria after 14 patients with chronic allograft dysfunction were converted from calcineurin inhibitors (CIs) to sirolimus without changing concomitant immunosuppression or antihypertensive treatment. METHODS: Creatinine, glomerular filtration rate (GFR), proteinuria, renal functional reserve (RFR) and effective renal plasma flow (ERPF) were determined before and 8 months after conversion. Intraglomerular pressure (P(G)), afferent arteriolar resistance (AAR) and efferent arteriolar resistance (EAR) were calculated using Gomez's formula. RESULTS: Creatinine (1.97 vs 2.075 mg/dl; P = 0.270) and GFR (40 vs 43 ml/min; P = 0.505) remained unchanged, proteinuria increased (338 vs 1146 mg/24 h; P = 0.006), RFR decreased (34.84 vs 13.47%; P = 0.019), ERPF (248 vs 310.6 ml/min; P = 0.0625) and P(G) (42.72 vs 46.17 mmHg; P = 0.0625) tendentially increased and AAR tendentially decreased (14.12 vs 10.28 dyne/s/cm(5); P = 0.0625). CONCLUSION: After conversion, P(G) shows a tendency to increase and RFR decreases significantly-characteristics of hyperfiltration, which could possibly partially explain the increase of proteinuria. Therefore, the application of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers seems promising. To avoid hyperfiltration, conversion should be performed early when renal insufficiency is still moderate.

Modulation of osteoblast activity by serum from diabetic and non-diabetic patients on hemodialysis: a three-dimensional culture study.

BACKGROUND: The aims of our study were to develop a three-dimensional model based on normal human osteoblasts and to determine, with this method, the osteoblastic response to sera of non-diabetic and diabetic patients on hemodialysis for chronic renal failure. METHODS: A protocol for culture of osteoblastic cells in three-dimensional meshworks of bovine type I collagen was developed. The effect on cultures of sera from three groups of patients was studied: 1) 12 diabetic patients on hemodialysis [age: 65 +/- 5.2 years; sex: 6 men, 6 women; duration of dialysis treatment: 21.25 (641) months]; 2) 12 non-diabetic patients on hemodialysis [age: 65.5 +/- 5.4 years; sex: 6 men, 6 women; duration of dialysis treatment: 21.35 (6-40) months]; and 3) 12 healthy volunteer donors (age: 64.2 +/- 4.9 years; 6 men, 6 women). The three-dimensional cultures obtained were processed in the same way as undecalcified bone biopsies, sectioned and stained. A histomorphometrical study was conducted. Parameters calculated were cell number, volume of newly-formed collagen, volume of newly-formed collagen per cell, mineral volume and mineral volume per cell. RESULTS: Number of osteoblastic cells was significantly higher in non-diabetic than in diabetic and control serum-treated cultures. Newly-formed collagen volume was significantly higher in non-diabetic serum-treated cultures than in controls. Deposited mineral volume was significantly lower in diabetic and non-diabetic serum-treated cultures compared to control serum-treated cultures. CONCLUSIONS: The model of three-dimensional culture proposed in the present study is useful in the study of different osteoblast functions including the rate of collagen formation and mineralization.

Tubular and interstitial expression of ICAM-1 as a marker of renal injury in IgA nephropathy.

BACKGROUND: The upregulated renal expression of intercellular adhesion molecule 1 (ICAM-1) is associated with glomerular and interstitial infiltration of leukocytes. AIM: To test the hypothesis that renal expression of ICAM-1 may be predictive in the highly variable IgA nephropathy (IgAN). METHODS: ICAM-1 (CD54) in tubular epithelium and interstitial leukocytes, macrophages (CD14), and T cells (CD3) were assessed using avidin-biotin-peroxidase in renal biopsy specimens from 45 patients with IgAN and from 29 patients with no glomerulonephritis. RESULTS: In IgAN, tubular ICAM-1+ was seen in 25 of 45 (55%) biopsy specimens, associated with glomerular hypercellularity, glomerulosclerosis involving less than 50% of the glomerular area, interstitial cellular infiltration, tubular atrophy, and proteinuria (U = 44, p = 0.005). Interstitial ICAM-1+ leukocytes were correlated with glomerulosclerosis involving less and more than 50% of the glomerular area, tubular atrophy, interstitial fibrosis, and serum creatinine concentration (r = 0.6343, p < 0.001). In patients with an increase of 50% in the serum creatinine concentration, interstitial ICAM-1+ leukocytes and CD14+ and CD3+ cells were significantly more numerous than in patients with a stable creatinine concentration. In patients with no glomerulonephritis, tubular ICAM-1+ was seen in 7 of 29 (24%) biopsy specimens, inversely correlated with the number of normal glomeruli and associated with glomerulosclerosis covering more than 50% of the glomerular area, tubular atrophy, and creatinine. CONCLUSIONS: Tubular and interstitial expression of ICAM-1 can be a marker of tubulointerstitial disturbance in IgAN. Interstitial ICAM-1 may be an adverse predictor of disease progression.

Expresión renal de la molécula de adhesión intercelular-1 (ICAM-1) en la nefropatía mesangial por depósitos de IgA. Un marcador de lesión tubulointersticial / Renal expression of ICAM-1 in IgA nephropathy. A marker of tubulointersticial injury

FUNDAMENTO: Conocer el significado clínicopatológico de la expresión renal de ICAM-1 en la nefropatía mesangial por IgA (NIgA). PACIENTES Y MÉTODO: Se identificó la expresión tubular e intersticial ICAM-1 (CD54) en 45 pacientes con NIgA y 29 pacientes con nefropatía no glomerulonefritis (NnoGN), analizándose su relación con la histología y la clínica en el momento de la biopsia renal y al cabo de 2,4 (2) (media [DE]) años en la NIgA y de 1,8 (1,5) años en la NnoGN. RESULTADOS: En 25 biopsias de NIgA (55 por ciento) se apreció expresión de ICAM-1 en el túbulo asociada a proliferación extracapilar (p < 0,05), así como esclerosis glomerular menor del 50 por ciento del área glomerular (p < 0,005), infiltración intersticial (p < 0,001) y atrofia tubular (p < 0,001). La proteinuria fue de 2,7 (1,5) g/24 h en los pacientes con expresión ICAM-1 en el túbulo y 1,5 (1,8) (p = 0,005) en los pacientes sin esta expresión. El número de leucocitos intersticiales ICAM-1 positivos fue de 234 (307)/mm2, y se correlacionó con la esclerosis glomerular en menos (r = 0,386; p < 0,05) y en más (r = 0,549; p = 0,01) del 50 por ciento del área glomerular, con la atrofia tubular (r = 0,442; p < 0,05); con la fibrosis intersticial (r = 0,405; p < 0,05) y con la creatinina (Cr) sérica (r = 0,6343; p < 0,001). Los pacientes con un incremento del 50 por ciento o superior de la Cr inicial presentaron 516 (360)/mm2 leucocitos intersticiales ICAM-1 positivos, frente a 66 (87,8)/mm2 p < 0,005) en los pacientes con Cr estable. En la NnoGN, 7 de las 29 biopsias (24 por ciento) presentaron ICAM-1 en el epitelio tubular. Hubo correlación inversa entre túbulo ICAM-1 positivos y glomérulos normales (r = -0,374; p < 0,05) y asociación con la esclerosis en más del 50 por ciento del área glomerular p < 0,005) y la atrofia tubular (p < 0,05). El número de leucocitos intersticiales ICAM-1 positivos fue de 191 (113)/mm2. Hubo correlación (r = 0,4356; p < 0,05) entre túbulo ICAM-1positivos y Cr en el momento de la biopsia. CONCLUSIONES: La expresión tubular e intersticial de ICAM-1 podría ser un marcador de lesión tubulointersticial en la NIgA. La presencia de ICAM-1 intersticial más que ICAM-1 tubular indicaría la progresión de la enfermedad en la NIgA (AU)